The Use of Evidence During an Interrogation: Part II

Written By: Reid
Sep 01, 2003

In the earlier web tip a fundamental principle of interrogation was presented: A guilty suspect may be persuaded to tell the truth if he is convinced that the investigator is absolutely convinced of his guilt. In some cases the suspect's guilt is, in fact, almost certain because of actual evidence collected against the suspect. Under this circumstance, most suspects readily confess. Unfortunately, many interrogations are conducted when there is very limited direct evidence supporting the suspect's guilt. In other words, the primary reason the interrogation is conducted is in an effort to either develop sufficient evidence to prove the suspect's guilt or develop information that will exonerate the suspect.

When the decision to interrogate a suspect is based essentially on circumstantial or testimonial evidence, it may be necessary to introduce evidence that does not actually exist. Before doing so, an investigator should be aware of the legality of this tactic. The landmark decision addressing the issue of engaging in deception during an interrogation is Frazier v. Cupp, 1969 U.S. The Court ruled that deception by an investigator is generally permissible provided that it does not shock the conscience of the community or court.

In addition to the legal constraints of misrepresenting evidence, an investigator must also consider the psychological risks of making false statements to a suspect during an interrogation. An investigator will only succeed in persuading a suspect to tell the truth if the suspect trusts what the investigator is saying. Furthermore, during an interrogation a suspect has a heightened level of suspicion and will pick up on the slightest misstatement by the investigator and use the error to fortify his resistance to tell the truth. Because of this consideration, our staff rarely lies about having evidence against a suspect during an interrogation.

Consequently, an investigator should consider misrepresenting evidence to a suspect during an interrogation only as a last resort when other persuasive efforts have been ineffective (and the investigator is still convinced that the suspect is guilty). There are, however, tactics to introduce fictitious evidence during an interrogation that do not involve deception at all. We recommend that these be tried before an out-right misrepresentation of the evidence.

The Implication of Evidence

Often an investigator will know, based on the crime scene analysis or the victim's account, what the guilty person must have done during the commission of a crime. For example, going into an interrogation the investigator may know that a gun used in a homicide was thrown into a nearby garbage can or that a diamond ring stolen during a burglary was pawned for $250 at Larry's Pawn Shop by a person somewhat matching the description of the suspect. Armed with this inside information the investigator may state during the interrogation, "We know that after you did this you threw the gun into a garbage can on Madison Street" or, "We know that you pawned a diamond ring taken from that home and got $250 bucks for it from Larry's Pawn Shop". When guilty suspects hear these statements, it has been our experience that they almost always accept them as fact rather than ask the obvious follow-up question "How do you know that?" A suspect who is innocent of the crime, of course, would not ask about how their guilt was revealed, but rather would adamantly deny engaging in the activity.

A second technique to imply the existence of evidence that does not really exist is to bring it up "inadvertently" during an interrogation. Consider the case of a suspect being interrogated on the issue of accepting illegal kick-backs. The investigator may make a statement similar to the following, "We know when it happened, how it happened and where it happened. Before you came in here I was sitting down with the other investigator reviewing the tape o well, forget about the tape, but we were talking about this thing and wondering how long you've been doing this." When an investigator tells a suspect to forget about a piece of evidence that apparently should not have been mentioned, it adds tremendous credibility to the actual existence of the evidence.

Evidence Will Exist in the Future

It can be an effective interrogation technique to discuss incriminating evidence as existing at some future point in time. As an example, the investigator may state, "We both know that they're going to find your DNA on the victim!" Under this circumstance, the suspect cannot challenge the investigator's statement by demanding to see the crime lab report because it does not yet exist. On the other hand, the investigator must select evidence that the guilty suspect knows could exist. When interrogating a career burglar, for example, it may actually be counterproductive to state, "We both know that they'll find your fingerprints inside that apartment!" since it is likely the suspect wore gloves during the burglary. In this regard, evidence that is generally safe to talk about as existing in the future include:

1. The accomplice will eventually tell the truth

2. A witness will be able to place the suspect at or near the crime scene

3. Transfer evidence (clothing, hair follicles, carpet fibers) will link the suspect to the crime

The Use of the Bait Question to Select Evidence

To select possible fictitious evidence to use during an interrogation, the investigator can "test" the evidence through the use of a bait question asked during the interview. A bait question suggests the possibility of evidence existing that would implicate the suspect in the crime. Examples of bait questions include, "If we were to check your phone records, would we find any calls made to (victim)?" or, "If we were to review the surveillance video at the store, would it show you there at the time this credit card was used?" If a suspect's response to the bait question is an emphatic and immediate denial, that piece of evidence should not be used as fictitious evidence during the interrogation. In the case of the phone records, the suspect may have called the victim from a pay phone or in the case involving the use of a stolen credit card, the suspect may have sold the card to someone else. In both cases, even though the suspects are guilty of the crime, they are not concerned about the suggested piece of evidence implicating them.

On the other hand, if the suspect's response to the bait question during an interview is a weak or qualified denial accompanied with nonverbal indications of deception, the suspect is obviously concerned that the evidence could exist. Under this circumstance it would be appropriate, during the interrogation, to tell the suspect something like, "When we check your phone records you know that we will find out that you called (victim)!" or, "Once we review the surveillance video we both know its going to show you inside the store when that credit card was used!"


An investigator should exercise caution when introducing fictitious evidence during interrogations of the following classes of suspects:

1. Youthful suspects

2. Suspects of lower intelligence

3. Suspects who claim that they cannot remember committing the crime because of some condition such as drug or alcohol consumption, epilepsy, head trauma, repression, etc.

Statistics demonstrate that the first two suspect classes represent a disproportionate number of false confessions. Some youthful suspects, or suspects of lower intelligence may place greater weight in the investigator's statements than in their own knowledge of their innocence. In other words, if an investigator lies about finding the suspect's fingerprints on a knife used in a stabbing, the suspect's immature logic may argue that the investigator must be correct and the suspect's inability to remember the stabbing is the result of being young or having a low intelligence. Contributing to this is the suspect's willingness to please the investigator by acknowledging the crime and the failure to appreciate the full consequences of such an admission.

In the instance of a suspect who claims to have no recollections at the time of the crime, it is almost impossible, based on demeanor or investigation, to determine if the reported amnesia is factual or merely a ruse to avoid accepting responsibility for committing the crime. Under this circumstance, for legal and ethical reasons, it is recommended that the investigator consider the reported amnesia as legitimate until proven otherwise. In light of this, the amnesic suspect's mind must be considered a blank slate at the time the crime was committed. If the investigator lies about having evidence which implicates the suspect in the crime, he is writing false information on that slate which may lead an innocent suspect to conclude that he must be guilty of the offense.


1. Never reveal evidence during an interview until first giving the suspect an opportunity to volunteer the information.

2. Generally start the interrogation with a statement indicating high confidence in the suspect's guilt, but do not refer to specific evidence.

3. Do not bring out evidence too early during an interrogation. Generally wait for an impasse when the interrogation seems to be stalling before mentioning specific evidence.

4. When actual evidence is introduced imply that the evidence presented it is only a small part of everything that has been collected.

5. While lying to a suspect about possessing incriminating evidence is generally legally permissible, psychologically it is a risky tactic and should be considered only when other efforts to persuade a guilty person to tell the truth have failed.

6. Consider implying the existence of evidence by stating something like, "We know that you..." or by "inadvertently" introducing evidence and then retracting the statement.

7. Consider a statement that refers to the evidence existing in the future.

8. Exercise caution when introducing fictitious evidence during the interrogation of youthful suspects, suspects with low intelligence or suspects who claim to have a memory failure at the time of the crime.

For further information on the use of evidence during an interrogation, consider attending our advanced course on interviewing and interrogation.

Permission is hereby granted to those who wish to share or copy this article. In those instances, the following Credit Statement must be included "This Investigator Tip was developed by John E. Reid and Associates Inc. 800-255-5747 /" Inquiries regarding Investigator Tips should be directed to Toni Overman