Main Body

Chapter 7: Witness Management

“Different types of witnesses will provide evidence from different perspectives, and these perspectives need to be assessed by the investigator to establish the reliability of the evidence provided.”

For any investigation, the details of events provided by witnesses are a critical element of the evidence gathered. Witness testimony is the verbal account of events or knowledge of the facts relevant to the crime. Witness statements will assist the investigator in forming reasonable grounds to lay a charge and will assist the court in reaching a decision that the charge against an accused person has been proved beyond a reasonable doubt.

As the law has evolved regarding witnesses, many rules of evidence, definitions, and protocols have developed to govern the way witnesses may testify in court. It is important for an investigator to understand these elements as this allows an investigator to evaluate witnesses and collect witness evidence that will be acceptable to the courts. The purpose of this chapter is to discuss the following concepts as they relate to the process of witness management.

  1. Identifying witnesses
  2. Defining witness types
  3. Defining competence and compellability
  4. Identifying the witness/suspect dilemma
  5. Witness credibility assessment
  6. The truthfully-incorrect witness
  7. Recognizing dominant witness influences and conformity
  8. Dealing with uncooperative witnesses
  9. Conducting witness interviews
  10. The field interview

Topic 1: Identifying Witnesses

It is sometimes the case that persons found as apparent witnesses to an event do not always provide accurate information about their identity. The reasons for this deception can vary from actual involvement in the crime to fear of reprisals from the suspect to simply not wanting to become involved with the criminal justice system. Regardless of the reason, it is imperative for an investigator to verify the identity of each witness. This can be best achieved by viewing a valid photo ID or, in the absence of photo ID, by establishing the witness’ identity through other means, such as police records, confirmation of identity, or verification of identity by a credible third party.

Topic 2: Witness Types

Once the identity of a witness has been determined, an investigator needs to establish an understanding of the witness classification. Different types of witnesses will provide evidence from different perspectives, and these perspectives need to be assessed by the investigator to establish the reliability of the evidence provided. This is important for several reasons, including that if charges ever go before the court, a judge will also consider these witness types and apply appropriate rules of evidence and levels of probative value to the evidence each type of witness provides.

Eye Witnesses and Corroborative Witnesses

As discussed in previous chapters, evidence can be classified as either direct evidence indirect circumstantial evidence. An eyewitness is a person who directly saw the criminal event take place, while a corroborative witness is a person who can only provide circumstantial or indirect evidence of the events surrounding the crime. For example, consider two scenarios where a young cashier is shot to death during the robbery of a convenience store. In the first scenario, one witness is found at the scene of the crime when the police arrive. This witness was a customer inside the convenience store. She saw the robber walk up to the counter, raise his handgun, and shoot the cashier. This witness can identify the suspect. In the second scenario, the witness is a customer who was walking up to the front of the store when he heard what sounded like a gunshot. He then saw a man running out the front of the store with a handgun in his hand. Upon entering the store, he saw the cashier had been shot. He can identify the suspect.

In both scenarios, a male suspect is apprehended in possession of a handgun only two blocks away from the scene of the crime. In the first scenario, the witness would be classified as an eyewitness; but in the second scenario, the witness would be a corroborative witness.

In the described scenarios, both witnesses can provide valuable testimony; however, the evidence of the eyewitness in scenario one would be given more weight at trial because there is a direct connection that the accused committed the offence through direct evidence, and the court would not need to make any interpretation on the veracity of any circumstantial evidence. The witness was present and saw the suspect shoot the victim. The corroborative witness in the second scenario provides strong circumstantial evidence to suggest that the man running from the store committed the shooting; however, additional investigation would be needed to support the circumstantial assumption that the person seen running from the store committed the shooting.

Clearly, eyewitnesses are the type of witness that investigators hope to find in their investigative efforts. Any police investigator will tell you, eyewitnesses are frequently not present at the scene of a crime, and therefore investigators need to be skilled at discovering additional physical and circumstantial evidence that can assist the court in reaching its conclusions in relation to the evidence of a corroborative witness.

In the second scenario, additional evidence that might assist the court to reach a conclusion that the suspect running from the store was the shooter might include the following: ballistics from the handgun seized from the suspect matching the fatal bullet found in the body of the accused, gunshot residue from the hand of the suspect showing that he had recently fired a weapon, and/or conclusive information indicating that the suspect and the shooting victim were the only two persons inside the store at the time of the shooting.

This is not to say that these same items of additional evidence would not also be useful to corroborate the witness in the first scenario. The difference is that, in the case of an eyewitness, the additional evidence is a value that is added, while in the case of the corroborative witness, more evidence is required to support the conclusion of guilt beyond a reasonable doubt.

Independent Witness

In addition to considering the evidence of a witness based on being an eyewitness or a corroborative witness, the court will also give additional weight to evidence that comes from a person who is an independent witness. An independent witness is sometimes referred to as a third-party witness. They are characterized as independent because;

  • They are not associated with the victim
  • They are not associated with the suspect
  • They are not in any way associated to the criminal event

In other words, an independent witness is someone with nothing to lose and nothing to gain by the outcome of the case. With this inferred lack of vested interest to either side, the independent witness is seen by the court as providing unbiased testimony. Similar to the court, an investigator can attribute more confidence to statements made by persons who are established to be independent eyewitnesses or independent corroborative-witnesses to an event.         

Topic 3: Competence and Compellability

For a person to be called as a witness to testify in court, that person must be accepted by the court as being both a competent witness and a compellable witness. There are some rules that apply to assessing both competence and compellability of witnesses, and it is important for an investigator to understand these rules and definitions since it can negatively affect a case if key evidence is expected from a witness who is found either not competent or not compellable to testify. The examination here is not intended to be a comprehensive review of the rules of competence and compellability, but an overview of the main statutory issues. Case law relating to the finer points of witness competence and compellability is constantly evolving and, where applicable, may be presented in a court to challenge a witness.

A Compellable Witness

Most of the people an investigator will encounter during their investigations will be considered compellable to testify. Any person can be compelled to attend court as a witness by way of issuing a subpoena. If they fail to attend court after being served with a subpoena, the court may issue a warrant for the arrest of that witness to bring them before the court to testify. That said, once a person is compelled to attend court by either a subpoena or a warrant, there are still certain circumstances under which that person may be considered exempt, or not compellable to provide certain types of testimony. These circumstances relate to when the witness is an accused person or when the witness is the spouse of the accused.

  1. An accused person cannot be compelled. Under Sec 11 of the Canadian Charter of Rights and Freedoms (1982), an accused person cannot be compelled to testify at his or her own trial. However, if the accused person is charged jointly with another person, they may be compelled to testify against their co-accused. Under those circumstances, the witness can be afforded protection under the Canada Evidence Act (1985) and their testimony cannot subsequently be used against them at their own trial for that same offence.
  2. When the witness is married to the accused. To preserve the privilege of communication between two partners in their marriage, legislation and case law provides a protection of privacy, and anything said between two married partners in relation to a criminal event cannot be compelled as testimony in court. This exemption to testify is stated under the Canada Evidence Act (1985). Specifically, Sec 4(3) states:

No husband is compellable to disclose any communication made to him by his wife during their marriage, and no wife is compellable to disclose any communication made to her by her husband during their marriage.

Many people incorrectly believe that this is a blanket protection where one spouse cannot testify against the other. However, the legislation only provides protection to the communication between spouses. It does not restrict a spouse being called to testify regarding observations of physical evidence or relationships. For example, a husband may arrive home covered in blood and carrying a bloody knife confessing to his wife that he just stabbed someone to death. Although the communication of the confession of the crime would not be compellable testimony, the observations of the blood, the knife, the time and location of the observation would be a compellable testimony. On this point, Sec 4(2) of the Canada Evidence Act (1985) also states:

No person is incompetent, or compellable, to testify for the prosecution by reason only that they are married to the accused.

In addition to the ability to call a spouse to testify regarding observations of evidence, the prosecution can compel a spouse to give evidence, including personal communications, for the prosecution in cases that involve an offence of violence against that spouse and certain sexual offence against children.

A Competent Witness

Like the rules of compellability, persons are presumed to be compellable to testify unless they meet the exceptions stated under the Canadian Charter of Rights and Freedoms or The Canada Evidence Act. All witnesses are also considered competent to testify unless it can be shown that they lack certain personal abilities or capacities. Historically, common law barred certain people from testifying. These people included convicted criminals, very young children, the mentally ill, and spouses of an accused person.

Many of these rules have been overturned by statute, for example, the rule against convicts was removed by section 12 of the Canada Evidence Act (1985). The record of a convicted person can still be used as character evidence.

There are three classes of exceptions; children, persons with low mental capacity, and spouses. For each of these classes of people, it is up to the opposing counsel in court to make a challenge and establish the incompetence of the witness.

There is a presumption that the witness possesses both capacity and responsibility to give evidence. To testify, a witness needs only the ability to recall what they have seen and heard, and be able to communicate what they recall. To communicate, the witness must be able to understand and respond to questions, and the witness must demonstrate the moral capacity to tell the truth. Moreover, the determination of competency is guided by the following rules established in case law:

The proof of competency or incompetency is on the balance of probabilities (R v Ferguson, 1996).

Where competency is challenged, it must be established by a voir dire before the witness can be sworn (R v Steinberg, 1931).

A witness who states that they may not tell the truth is still competent to testify. Such issues of truthfulness are factors of credibility for the trier-of-fact (R v Walsh, 1978).

When considering the issues of witness competence and compellability, an investigator must keep in mind that the evidence collected from certain witnesses, such as spouses, children, and persons of low mental capacity, may be subjected to these rules. Exemptions for witness testimony and exclusion of the evidence may occur at trial (R v Khan, 1990; Justice Canada, 2017).

That said, during the investigation, it remains within the purview of the investigator to assess the information and evidence collected, and to consider that evidence when forming reasonable grounds to believe and take action. When considering the nature of the information and evidence received, it is not up to the investigator to assess whether the court will accept the information or not. The investigator’s use of the information and evidence received from a spouse, a child, or a person of low mental capacity should not be discounted in forming reasonable grounds simply in anticipation of a possible exemption of the witness and exclusion of evidence by the court. If the person giving the information or evidence is assessed as being a credible witness, the investigator should consider that material and give it fair weight in forming reasonable grounds for belief.

Topic 4: The Witness/Suspect Dilemma

Although the circumstances vary, it is a common occurrence that crimes are reported by a perpetrator posing as a victim or a witness. Crimes, such as break-and-entry and motor vehicle thefts, are quite often insurance frauds. Other crimes, including murder, have also had the offender make the report as a witness to explain their presence at the crime scene and avoid being considered as a suspect. Being aware of this possibility requires investigators to undertake a process of validating the reported crime and assessing the information being reported by witnesses or victims as a routine part of their investigation. To do this, an investigator should be attentive to questioning the report and the evidence presented to assess:

  1. Did the crime happen at the time being reported?It is often difficult for a person fabricating a report to provide the true timing of the events without implicating themselves as present at the time of the crime. Asking questions that demand timelines accounting for witness activities during the crime time can sometimes detect deception.
  2. Did the crime happen at the place being reported?Persons fabricating a report will sometimes change the location of the reported crime to avoid detection of the true crime scene where incriminating physical evidence may still be present. Carefully assessing the report in comparison to evidence present or not present can sometimes indicate this deception.
  3. Did the crime happen in the manner being reported?False accounts of crime will often exaggerate or over report details of the event. The report will contain some level of fabrication that explains their own connection to the events. Assessing each witness version of the event for consistency or inconsistency with physical evidence and other witness versions can reveal deception.

Even with careful attention to these questions, it may not be immediately possible to confirm the validity of the crime being reported, and the investigation must proceed to take the report as true until other evidence emerges to prove otherwise.

The advantage of investigating this kind of falsely reported crime is that the suspect is presenting themselves as a witness or victim. As such, all of their statements may be taken and will be admissible against them later, without voir dire, if deception in their statement becomes provable. Until some distinct piece of incriminating evidence emerges, the investigator is under no obligation to caution or warn the witness. Each new statement can afford opportunities to investigate further in search of evidence of the lie that will prove deception.

Topic 5: Witness Credibility Assessment

In addition to determining if a person is an eyewitness, a corroborative witness, an independent witness, a competent witness, or a compellable witness, every person who is a witness during an investigation needs to be subjected to a credibility assessment. As information and evidence are collected from each witness, it is part of the investigator’s job to determine the level of confidence that can be attributed to each witness. This is called witness credibility assessment.

One of the most significant issues to be considered in assessing a witness is determining if they are a witness, or if they are a suspect posing as a witness. More likely than interviewing false reporters of crime, investigators find themselves interviewing a variety of ordinary people who truly have been the victim of a crime, have witnessed a crime, or witnessed some aspect of a criminal event. The level of confidence an investigator can have in a witness will be contingent on several factors relating to who the witness is, the abilities of the witness, and the circumstances of the event.

  1. Witness profile. Ideally, every witness would be an upstanding member of the community with a high level of integrity and an outstanding reputation. This is rarely the case. The nature of criminal activity and the natural proximity and association of criminals within a criminal community, often skew the witness list more towards those with more colourful and less upstanding personal profiles. Being part of the criminal community, or having a criminal record, does not necessarily mean that a witness will not be truthful. However, these are factors that an investigator must consider when assessing the value of the evidence being reported. For example, if a witness has a record for perjury, their evidence should be carefully scrutinized and additional corroboration may be required to strengthen the witness’ account of the events to achieve acceptable credibility for the court.
  2. Witness bias — motivation to lie. As discussed earlier in this chapter, independent witnesses who are not connected to the victim, the accused, or the event itself make the most credible witnesses. People close enough to a criminal event to become witnesses are often, in some way, related to the victim, the suspect, or to the event itself. As such, the associated witness may have a bias in making their report of the event. As a friend or foe, the witness may have some motivation to withhold information or to lie to influence the outcome. Understanding how each witness fits into the event, and what their linkages are to other participants or the event itself, is an important dynamic to uncover. In the case of a bias witness, additional corroboration should also be looked for.
  3. Witness involvement — emotional impact of the event. Criminal events can be very stressful and anxiety producing experiences. This is not only true for the victim but for anyone who has been exposed to danger, violence, or situations where threats to personal safety or incidents of injuries or death have occurred. As human beings, we are not conditioned to live through these kinds of events without experiencing some kind of emotional response. Post-Traumatic Stress Disorder speaks directly to the emotional damage traumatic events can inflict (Resnick, Kilpatrick, Dansky, Saunders, & Best, 1993). It is important for an investigator to consider the nature of the event and the exposure of the witness to these dynamics. Extreme post traumatic trauma, such as observing the violent death of a loved one, can sometimes render that witness unable to provide a reliable account of details (Streets, 2011). It may be necessary to give some witnesses time to regain their composure to provide information or evidence. In some cases, the traumatic effect is too significant and the information cannot be recovered. Knowing how a witness is connected to the event and being able to comprehend their potential exposure to emotional trauma provides the investigator with the insight that certain strategies, such as softer interview techniques, flexible timing, and professional support resources that take the emotional trauma of the witness into consideration, may be necessary and appropriate. Another kind of emotional trauma is a witness’ fear for their personal safety. This can be a fear of physical, psychological, or emotional reprisals for the witness providing evidence. In a situation that includes organized criminal groups, this fear is a genuine and understandable concern. In these types of cases, it may be difficult to protect the identity of a witness, and assurances of protection of the witness can be subject to jurisdictional or organizational limitations of witness protection resources.
  4. Location when viewing the event. A witness’ physical location when observing an event can become an important point of evidence, and should be considered and included in the interview and statement of each witness. If a witness is providing details of the event that required them to be in direct proximity of the accused or the event to observe or hear, the physical location of the witness at the time of those observations is a critical element. Physical location can also be important in explaining gaps or differences in witness observations. The fact that one witness to a crime observed certain actions, but another witness did not, can sometimes be explained by the alternate angles of observation of each witness or because of some physical obstruction that affected one witness but not the other. Crime scene photos and diagrams can often help witnesses to demonstrate and describe their distinct perspectives. Returning to the scene of the crime to physically establish these locations and angles of observation can be a useful exercise for investigators to conduct.
  5. Awareness of the crime — intent to observe and recall the occurrence. In most cases where a crime has occurred, a witness will know that the crime is happening, and this awareness will engage their attention to make observations that they can later recall and give an account of. In other cases, where a witness has not been alerted to the crime and is only observing the evolution of events as part of an unremarkable sequence, their memory is not as engaged and their processes of observation may not be as keen. To demonstrate this point, consider an example where a group of three people are standing in the teller’s line at a bank.


    At the front of the line, a young man hands the bank teller a note advising, “This is a robbery. I have a gun. Put all the cash from your till into an envelope and give it to me. Do not press the alarm or I will shoot you.” The bank teller is aware that a crime is taking place; however, the two customers standing in line behind the robber are simply waiting their turn. The customer standing immediately behind the robber suddenly notices that the teller looks frightened and sees she is placing the contents of her cash drawer into an envelope. The third customer in line remains unaware and is talking on the telephone to his wife about their grocery list. The robber grabs the cash-filled envelope from the teller and turns to run out of the bank. The customer immediately behind him steps out of his way, but he bumps into the third customer still talking to his wife. In this scenario, an investigator could expect to get a detailed account of the events from the bank teller who was engaged in the event and aware of the crime from the outset. The customer immediately behind the robber become aware of the crime and was making observations half way into the robbery. This customer could likely provide some significant details. The third customer in line was never aware that a crime was in progress and, other than perhaps providing a limited description of a man who bumped into him, his value as a witness may be negligible. Many witnesses who make observations of a criminal’s activities in the pre-crime stage or in the post crime stage, when they are leaving the scene of the crime, fall into the category of not being aware of the crime. This does not mean these witnesses will be of no value but that their casual observations need to be identified and recorded as soon as possible.

  6. Length of observation time. Very simply, length of observation time is the amount of time a witness had to see the event taking place. This amount of time will vary with circumstances, as there would be a difference in opportunity for observation between one witness standing stationary at the crime scene observing the event, and another driving past the unfolding events at 100 kilometers per hour. This can also be an issue contingent upon the awareness of the event taking place. Some witnesses become aware of the event more quickly and have a longer opportunity to observe. As with our example of the bank robbery, the teller being robbed had the longest observation time, the customer immediately behind the robber became aware that something was happening and had a shorter observation time, but the third customer did not become aware of anything until the robber bumped into him. This scenario demonstrates the value and detail of evidence an investigator might expect from witness with differing levels of observation time.
  7. Time elapsed between the event and the interview. A critical aspect of gaining the best account of events from any witness is making sure that the interview happens at the earliest opportunity. It is a practice in police investigation to make every effort to identify and interview witnesses as soon as possible. As a simple exercise to demonstrate the importance of finding and interviewing witness quickly, take a piece of paper and to the best of your ability, write down the details of your day starting at the beginning of the day three days ago. What did you do? Where did you go? Who did you see? If you are like most people, you have some level of daily structure to your life. From that structure, perhaps you will recall you got out of bed at a usual time. Maybe you went to work or stopped at the gym or at your favourite coffee shop on the way to work. These benchmarks of your daily routine may be easily remembered. But, on your way to work, did you happen to see a green van with extensive damage to the front end on the street near your home? Of course, this is a fictitious question, but this would be the kind of inconsequential daily observation information you might be asked to recall by police canvassing for witnesses to a crime.Understanding this time limited aspect of human memory, investigators need to consider how much weight they can place on the accuracy of information being recounted by a witness. If a witness is providing a remarkably accurate recollection of something being recounted from any distance in the past, it is a good idea to ask that person how they can recall what should be a mundane event with such a degree of accuracy or clarity. If they are correct, the witness will sometimes provide a memory trigger that made them notice and causes them to recall. For example, a witness may answer, “Yes, I remember that green van with all the damage to the front end because my brother has a green van just like that and I looked at the driver and saw that it wasn’t my brother. I looked at it even closer because I had never seen that van on my street before.”
  8. Ability to record or repetitively recount details. If a witness was aware that they had witnessed a crime and they were making a conscious effort to record or otherwise memorize the facts, this is a point that the court will be interested in hearing as part of the witness’ evidence. If, for example, to remember the licence number of a suspect vehicle, the witness repeated the number over and over until they were able to write it down, this is an important detail that should be recorded in the witness statement, and the paper upon which the number was written should be seized and retained as an exhibit that can be shown to that witness on the stand as the note they made at the time of the event. This demonstrated that the witness had intent to recall and record the details of an event, which will contribute in a positive way to the credibility of the witness.
  9. Physical abilities — hearing, sight, smell, touch, taste and cognitive perception. The physical faculties of the senses may be used by a witness in their recollection of the events they are describing. When a witness makes a statement referring to their senses, their credibility in giving that evidence will depend upon the extent to which their senses are working. In taking statements from witnesses, the investigator must be satisfied that a witness who claims to have seen an event has adequate vision to make that observation. Similarly, a person who states that they heard something must be able to demonstrate that they have adequate hearing to have heard it. Speaking very quietly to test the hearing limits of a witness or asking a witness to describe something within the visual ranges of the evidence they saw are both reasonable strategies to informally test a witness’s range or limitations of senses. Asking a witness questions about their use of eyeglasses, contact lens, or hearing aids during their observation of events are all reasonable strategies to establish the credibility of a witness to make the observations they are reporting. Flowing from the use of their senses, witnesses will often provide information and cognitive perceptions of the events they witnessed. The cognitive perceptions of a witness are their own personal interpretation of the information they took in through their senses. As such, they are a subjective analysis of the information being sensed. A witness may provide a statement regarding the age of a suspect, the size of an object, the speed of a vehicle, the smell of alcohol on a person’s breath, or even the distance they stood from the event they witnessed. To a certain degree, the court will allow such evidence and opinions of common knowledge from non-expert witnesses; however, a witness may be challenged on their observations, and it is best to understand any misperceptions in advance. Again, informal testing of a witness to become comfortable that their cognitive perceptions and subject interpretations are accurate and not significantly skewed is a reasonable way to test credibility. For estimating the age of a suspect, an investigator could ask the witness to point out other persons who are approximately the same age. Similar tests could be undertaken in testing perceptions of the size of objects, the speed of vehicles, and the distance to locations. For statements regarding observations, such as the smell of alcohol, the investigator should ask the witness to describe their personal experiences with alcohol to know that it was alcohol they smelt. If the witness had not experienced alcohol or been with people who were drinking alcohol, that opinion of smell would lose credibility.
  10. Cognitive capacity and age of witness. To establish the competency of either a child or a person of limited mental capacity, conducting a careful witness credibility assessment will be helpful for the prosecution in meeting challenges to competency. Part of the initial interview should seek to determine if the child or person of limited mental capacity understands the need to tell the truth. The competency background of the witness should be conducted by interviewing persons, such as parents, caregivers, teachers, or doctors, who know the witness and can attest to their mental capacity and their ability to understand questions and communicate their answers.The actual interview of both children and persons of low mental capacity are a delicate and time-consuming process. They must be conducted in a manner that is both suited to the maturity level of the witness, and structured using non-leading questions to elicit answers. In cases where it is possible, investigators with specialized training in this type of interviewing should be utilized. That said, in the first instance, at the scene of an event, it is important for the responding investigator to understand the special considerations that apply to this type of witness in consideration of their evidence. The goal in these cases is to determine how much weight can be attributed to the evidence being provided by witnesses. An investigator may determine that the evidence of a witness is credible and can be used in the development of forming reasonable grounds or, alternately, they may find that the credibility of the witness cannot be established, and the evidence cannot be used in the development of reasonable grounds to take action.

Topic 6: The Truthfully Incorrect Witness

As much as witnesses are a critical component of the criminal investigation process, they can also become a critical threat to the accuracy and integrity of evidence gathering. This sometimes occurs in an anomaly where an apparently credible, independent witness tells their version of events and they are significantly wrong in what they say they observed. Unlike cases where a witness is motivated to intentionally fabricate or exaggerate their account of events, the truthfully incorrect witness has no malicious intent and will provide their version of the events with a genuine belief that what they are saying is true and accurate. This type of witness is an independent observer with no motivation to lie, and as such the weight of their testimony can carry significant influence for the investigator’s reasonable grounds to believe and eventually carry significant probative value for proof beyond a reasonable doubt in the court. For investigators, the truthfully incorrect witness can become a paradox capable of misleading the outcome of the investigation resulting in a guilty suspect going free or an innocent suspect being arrested and charged. This anomaly of truthfully incorrect witnesses is an issue that investigators must remain mindful of. Witnesses are human and humans are fallible. Even for a witness who appears to be independent and credible, there remains a need to scrutinize and fact check the witness’s version of events against the known physical evidence and the accounts of other witnesses.

The importance of the investigator being mindful of a truthfully incorrect witness cannot be emphasized too strongly. In 1996, for example, the National Institute of Justice in the United States released a report concerning the implications of eyewitness testimony and false memories, and in it, reported that 90% of all DNA exoneration cases defendants were wrongly convicted upon the false memories of eyewitnesses (Brainerd, 2005). More recently, Smarlarz and Wells (2015), citing The Innocence Project, noted that eye-witness testimony was used to convict innocent people in over 70% of DNA exoneration cases. More recently yet, Rose and Beck (2016) note that eyewitness testimony accounts for more wrongful convictions than anything else. Research has shown that false memories in eye witnesses can be created in a number of ways, including through leading questions, reports from others, contact with other people, suggestions, a witness’ own expectations, the expectations of others, other social pressures, and media (Bennett, 2015; Allen, 1991). It has also been established that witness recall can be affected by stress (Morgan et al, 2004) and by alcohol (Oorsouw et al, 2015) in complicated ways.

Topic 7: Dominant Witness Influence and Conformity

One of the negative dynamics that can occur in an investigation where there are multiple witnesses is the contamination or influence of witness statements by a dominant witness. This influence can occur when witnesses to an event have not been separated before any interactions or conversations have occurred between the witnesses. These dynamics are possible in almost all cases, and an investigator must always be mindful that this potential exists. It is also possible that a dominant witness will boldly and sometimes aggressively state their version of the events, which can cause other less confident or less sophisticated witnesses to question their own perspective. In such cases, a less dominant witness may change their version of the events or even omit observations to conform to what the dominant witness stated.

Most susceptible to this kind of influence are very young witnesses, elderly witnesses, or witnesses who have timid personalities. On some occasions, where there is an imbalance of power or status in a personal relationship, or even in a subordinate organizational relationship, witnesses may conform to the more powerful witness out of fear of repercussions or hope of favour. In some cases, the dominant witness has a vested interest in having their version of the events stated their way, and the dominant influence towards the other witnesses is intentional and implicitly threatening in its tone.

In cases where witnesses have interacted prior to being interviewed, each witness should be interviewed in seclusion from the others. Witnesses should be asked if they have discussed the event with anyone else or heard anyone else’s version of what happened. They should be cautioned and encouraged to disregard anyone else’s version of events and limit their version to their own account of what was seen and heard during the event.

Topic 8: Uncooperative Witnesses

One of the many unpleasant dynamics of criminal activity is when the police attend the scene of a crime and witnesses, or even victims, refuse to cooperate with investigators. Sometimes, these uncooperative persons are part of the criminal lifestyle and are not willing or interested in cooperating in the justice system. The only strategy for police in these cases is to gather as much forensic evidence as possible in relation to the event and to seek charges where sufficient evidence can be found.

Although these uncooperative witnesses may believe they are not required to participate in the criminal justice system, it is entirely possible to subpoena an apparent witness to attend court to be questioned regarding the criminal event they witnessed. If that witness refuses to answer questions in court, it is possible for the judge to find them in contempt of the court and to sentence them accordingly. That said, this rarely happens.

Topic 9: Conducting Witness Interviews

Arriving at a crime scene, investigators are often confronted with a cast of characters who may be victims, witnesses, or suspects in the matter to be investigated. In the case of an active event, where immediate in-depth interviews are not possible, it is important to:

  1. Conduct immediate field interviews of each subject at the scene;
  2. Do an immediate preliminary classification of persons found at the scene as victims, witnesses, or suspects; and
  3. Take appropriate measures to separate the persons found at the scene for the purpose of physical security and protection of future testimony from cross-contamination of witness accounts and conformity.

Topic 10: The Field Interview

Attending the scene of an event, the first immediate field interview may be as simple as asking an apparent victim or a probable witness, “What happened here?” This simple question serves several purposes for the investigator. First, it shows that the investigator is not making any investigative assumptions based on what is visible to him or her at first glance. With this question, the person being asked is prompted to supply their own version of the event, as they saw it. This pure version will assist the investigator in developing a picture of the event, and it will provide a context allowing the investigator to classify the speaker as a victim, witness, suspect, or an uninvolved party.

If the person the investigator questioned turns out to be the perpetrator, and the investigator has no other evidence that suggests this person should be a suspect, any statement made by that person would likely be considered a spontaneous utterance and may be admitted in evidence without a voir dire. For example, consider a situation where an investigator arrives at the scene of a street fight where a man has been fatally stabbed. The investigator asks one of the men standing nearby, “What happened here?” and the man immediately says, “I killed him and he deserved it.” This statement would be considered a spontaneous utterance and would likely be admitted as evidence without the usual voir dire. Once this self-incriminating statement has been made, the suspect would need to be immediately arrested and provided with the Charter warning and caution before any further statements could be pursued through additional questioning. Clearly, once a suspect is identified, they can no longer be considered as a witness.

If no one is immediately identifiable as a suspect at the scene of an event, it is reasonable for the investigator to proceed with classifying the persons present as possible witnesses. As discussed earlier in this chapter, to classify the witnesses, the investigator must consider the nature of the evidence that the witness can provide:

  • Direct evidence of the eyewitness, which is evidence of seeing the criminal event occurring and perhaps even identifying the suspect; or
  • Circumstantial evidence of the corroborative witness, which is indirect evidence of events, physical evidence, timelines, and spatial relationships that can assist the court in reaching a logical presumption of how the crime occurred and who was responsible.

Interviewing a witness is not just a simple matter of hearing their version of the events. There are many factors that can come into play in determining how credible a witness is. Following the initial field interview, and once the event is under control, it is important to take the witness’ formal statement at the earliest available opportunity. Taking the witness statement should be conducted using the best technology available given the circumstances. If audio and or video recording devices are not available, or obtaining them would cause an unreasonable delay in getting the witness statement, a written statement should be taken. No matter how the witness statement is recorded, it should be the goal of the investigator to obtain the best, uninfluenced, and unbiased version of events from a witness.

Like the threat of conformity being induced by a dominant witness, a witness can also be influenced by leading questions asked by an investigator. Some witnesses are so eager to assist in solving the crime that they will attempt to guess the answer to a leading question instead of admitting that they do not know the answer. The caution here is to avoid asking leading questions. Leading questions are questions that a witness might be able to infer the answer by the nature of the wording. An example of a leading question would be:

“Did you see Larry pick up the revolver and shoot Bill in the head?”

This leading double question can be answered yes or no, and it also supplies the witness with a significant amount of information that the witness can infer about the details of the event. These may be details that they would not have previously known. From this question, the witness could infer that Bill was shot in the head, the weapon used was a revolver, the suspect in the shooting was Larry, and the revolver was picked up from somewhere. A better and more appropriate initiation of the statement would be: “Did you witness an event today? Tell me what you saw.”

Although this open-ended approach to statement taking is more time consuming, the investigator at least knows that they are not planting any ideas or words to influence the witness’ account of the event. Taking a statement in this manner is known as taking a pure version statement. A pure version statement needs to be the witness’s best, uninterrupted narration of the events, as they recall it. As the witness recounts their best memory of the event, the investigator must resist the temptation to intervene and ask clarifying questions on the points being revealed. Clarifying questions like the question used to start an interview can be leading and can influence the witness’ statement.

As the witness recounts their pure version of the events, the investigator should be taking notes on points to be clarified once the entire statement is completed. Those questions should remain as open-ended as possible. So, if the witness has stated in their pure version of events, “I walked into the room and that is when I saw the shooting happen,” the clarifying question should be an open-ended prompt, such as, “You said you saw a shooting happen, tell me more about that.”

There are many different techniques and strategies for witness interviewing that cannot be addressed in this short book as part of an introduction to investigations. The best advice for new investigators for the interviewing of a witness is learning to be patient and allow the witness to tell their story in their own time and in their own way. Avoid the human tendency of trying to assist and interact with the speaker by asking questions, filling in the blanks, and clarifying things while the story is being related. The more effective interview technique is one where the witness can exhaust their memory and relate the events to the best of their ability without interference and the contaminating influence of questions that might derail their train of thought.

As discussed earlier, it sometimes happens that a witness or a reporting victim will turn out to be the perpetrator of a crime. In these cases, allowing the person to provide their full uninterrupted statement can produce incriminating indicators or even evidence of involvement. There is a tendency for criminals who fabricate their report of a crime to make sure they are adding information in their statement that helps eliminates them as a suspect. This can include unsolicited alibis for their whereabouts and their activities at the time of the reported event. When a witness supplies this type of information without being prompted, it can be an indicator of personal involvement in the criminal event. Any such voluntary explanations of personal activities should be recorded carefully and closely scrutinized to confirm the validity of facts. Follow up questions to unsolicited explanations should include seeking the names of independent witnesses who might be able to corroborate the witnesses account.

In the case where an investigator suspicious that a reporting witness or victim may be the perpetrator of the crime, there is no obligation to reveal that suspicion until evidence exists that allows the investigator to form reasonable grounds for belief. If further investigation determines that the statement is a fabrication, this may be sufficient circumstantial evidence to require a warning for at least the offence of mischief for making the false report. In such circumstances, a Charter warning and caution are appropriate before additional questioning is undertaken.

Taking the Witness Statement

The written, audio, or video statement of a witness taken by a police investigator will become the permanent record of events as seen by that witness. The police investigator will use the content of that statement as a reference document in the construction of search warrants and in support of reasonable grounds for belief to lay an arrest. The crown prosecutor will use the statement to construct their case for presentation to the court and for pre-trial disclosure of the evidence to the defence counsel. The statement will serve as a document from which the witness may refresh their memory of events to provide accurate testimony to the court.

Considering the foregoing list of uses, the witness statement needs to be as accurate and complete as possible. The standard format used to begin a witness statement is as follows:

This is the statement of witness’s full name taken on date and time at location where taken by name of person taking or recording the statement.

At the conclusion of the statement, it must be signed by the witness. If the statement is audio and or video recorded, the foregoing preamble needs to be used to start the statement, and once the statement is transcribed, the witness should sign the hard copy transcription.

Witness Identification of a Suspect — Photo Lineups and Live Lineups

Beyond taking a statement, one of the most common forms of obtaining information from a witness is the practice of having witnesses identify a suspect through the viewing of photographs or photo lineups. This kind of after the fact identification of a suspect will be subjected to scrutiny when it is presented in court. Strict protocols must be followed to demonstrate that the process was conducted in a fair and unbiased fashion. Under no circumstances would an investigator ever present the witness with only a single photograph or a single lineup suspect and ask if this is the suspect. Additionally, under no circumstances should an investigator ever state that the suspect is one of the persons in the lineup.

In the practice of presenting photo lineups, the photos are arranged in a series of eight pictures or more that are permanently mounted into a series of numbered windows of a special photo lineup file folder.

Sample photo lineup. Long description available.
[Long Description]

The suspect’s photograph is one of the eight pictures and the remaining seven photos are called “distractor photos.” To be fair, these distractor photos need to be reasonably similar to the suspect photo in terms of gender, age, race, head hair, facial hair, and glasses. When the photo lineup is presented to the witness, there should be instruction by the investigator that the suspect of the investigation may or may not be in this photo lineup (i.e., “Please look at all the photos carefully and only select the number of a photo if you are certain it is the suspect you saw at the time of the event”).

Like photo lineups, live persons may be used to conduct a suspect identification or a suspect in custody. These live lineups are more difficult to create because they require the cooperation of the suspect and if the suspect does something during the viewing that could draw attention to him; it could prejudice the lineup process. As with the photo lineup, the distractor subjects need to be selected to be fairly similar to the suspect; however, unlike photo lineups, the live lineup requires the additional elements of ensuring that everyone is of similar height, weight, body shape, and dress. You cannot put the suspect dressed in a shirt and tie into a lineup with distractors wearing blue jeans and tee shirts.

Another means of suspect identification is permitting the witness to page through volumes of criminal file photos that are part of the local police photo collection. This technique is sometimes used when there are no identifiable suspects and the witness is reasonably certain that they will recognize the face of the suspect if they see it again. The negative aspects of this strategy are that it can take a great deal of time, and a witness can sometimes become confused by the process and overloaded with the viewing of too many faces, causing an eventual loss of confidence in making a proper identification.


This chapter examined the broad range of issues that must be considered by an investigator in relation to the collection of information and evidence from witnesses to a crime. These issues range from the way witness evidence is classified and validated to the way witnesses are assessed and evaluated to determine their ability to give evidence and the credibility of the evidence they give.

The chapter illustrated the processes required for proper witness management during investigations. These task processes of witness identification, classification, credibility assessment, and proper interviewing practices in statement taking are all components of witness management that demonstrate professional standards applied by a criminal investigator.

Study Questions

  1. What is a collaborative witness?
  2. What is an independent witness?
  3. Can an accused person be compelled to testify regarding a crime they have been involved in?
  4. Are all persons considered competent to testify?
  5. What is witness credibility assessment?
  6. What concerns should an investigator have about dominant witnesses?
  7. What should an investigator do in the case of an active event where immediate in-depth interviews are not possible?
  8. Is it possible to have a witness statement in something other than written form?
  9. What are two negative aspects of having a witness attempting to identify a suspect by paging through volumes of criminal file photos?

Long Descriptions

Photo lineup long description: A sample document asking the public to identify a suspect in a criminal investigation. Head shots of eight young men of similar age are numbered. Below, the document says, “The person that the police are seeking to identify in their investigation may or may not be one of the persons in the photo lineup above. If you positively recognize one of the photographs above as the person you saw, please write the number of that photograph in the space below.” Below, it says, “I recognize the person shown in photo #[blank],” and below that is space for “any comment regarding your observation” and the signature of the witness.

A disclaimer at the bottom says “Photos illustrated in this mock photo lineup are student photographs and have been kindly provided with the cooperation and consent of Law Enforcement Studies students and Bachelor of Law Enforcement Studies students from the Justice Institute of British Columbia.” [Return to Photo lineup]