It is rare to conduct an interrogation under circumstances where the investigator has absolute proof of the suspect's guilt. At the outset of most interrogations there is merely circumstantial or testimonial evidence which points to a suspect's probable involvement in the crime. The purpose for the interrogation is two fold: First, it is an attempt to learn the truth from the suspect, i.e., did this person really commit the crime? Second, If the suspect does confess, the investigator must then develop details about the suspect's crime to corroborate the confession and to be used as evidence in a court of law.
Most guilty suspects will certainly not tell the truth if the investigator openly acknowledges that a confession is needed to develop evidence to prove the suspect's guilt. Consequently, an interrogation relies extensively on pretense and innuendo. For an interrogation to be successful, the suspect must be convinced that the investigator already knows that he committed the crime.
There are a number of tactics an investigator uses to convince the suspect that his guilt is already known. At the outset of the interrogation the investigator tells the suspect that the evidence clearly indicates that he is the person who committed the crime. The investigator then makes a transition from the focus of the interview, which was whether or not the suspect committed the crime, to a new unanswered question, which is to learn the circumstances that led to the suspect's decision to commit the crime. Throughout this procedure the investigator attempts to dominate the conversation and makes no reference to specific evidence against the suspect (since there is usually no definitive evidence to present).
As the guilty suspect listens to the investigator's confrontation statement and the stated reason for the interrogation (to find out the circumstances that led up to the crime) his mind is focused on one question: "Does the investigator really know that I committed this crime?" The suspect's first tactic will be to deny involvement in the crime. The investigator will counter this by confidently restating his certainty that the suspect did commit the crime. This volley may go back and forth a few times before the suspect realizes that the investigator is not presenting any proof of his guilt. This realization invariably leads the suspect to make a statement such as, "What evidence do you have?" or, "Why do you think I'm the one who did this?"
When a suspect specifically asks about incriminating evidence during an interrogation the investigator must recognize that the suspect is actively looking for something tangible to attack. Consequently, this is generally not a good time to bring up specific evidence. The following dialogue illustrates the dangers of doing so:
S: "What evidence do you have that I did this?"
I: "You don't have an alibi for last Friday; you've got a prior record plus you failed the polygraph!
S: "Listen, there are probably 10,000 people in this city who were alone last Friday night and I'm sure that hundreds of them have a prior record. As far as the polygraph goes, that machine is not 100% accurate which is why it is not accepted as evidence in court. You don't have a thing on me!
Obviously, this interrogation is unlikely to result in a confession. The following responses have been used effectively by our staff to respond to the suspect's request for evidence during an interrogation:
Arguing Against Self Interest
"I would love to sit down with you and show you, piece by piece, all of the evidence we have collected in this case, but it is against department policy for me to do that. Eventually, you will be able to see all of the evidence but by that time my report will be turned in. That's why I'm talking to you now."
The above response is our standard response for most suspects who request to see evidence during an interrogation. It starts off with the persuasive tactic of arguing against self interest, e.g., "I wish I could show you all of the evidence. That would make my job really easy." It then offers a plausible explanation for not revealing evidence while, at the same time, making reference to the evidence (you will be able to see the evidence eventually). The response concludes by emphasizing the importance for the suspect to tell the truth at this time, which is also desirable.
"The whole reason I'm talking to you is to find out what your attitude is about this thing. If I have to lay out all the evidence before you tell the truth that tells me you're a common criminal who doesn't even deserve an opportunity to explain your side of the story. I had a guy in here on Monday who had stolen a purse from a lady and then grabbed the wallet from the purse and left the purse on the street. I was talking to him just like I'm talking to you and he says, eWhy do you think I'm the one who took that lady's wallet?' I didn't tell him that we lifted his fingerprints from the purse and that the lady identified him in a photo lineup. If I reveal the evidence that we have against a person then I can't evaluate their attitude about what they did."]
This response is appropriate for suspects who are emotional offenders and exhibit persistent but weak denials. The implication of the investigator's response is that somehow the suspect's attitude will be important for people to know. This concept is nicely reinforced with a third person theme. Hopefully, The suspect will not want to be like the other suspect who left without telling the truth.
Appealing to Logic
"I'm sure there are people you know well enough that when they didn't tell you the truth you knew. Maybe they were friends or family members but when they didn't tell you the truth you could tell, right? Well, that's what I'm trained in. That's what I do for a living. I'm not a goodcook. I can't build a house or fix a car. But I am very good at what I do which is telling when someone is telling the truth."
This response is effective for educated suspects with higher levels of social responsibility. These suspects rely on their ability to read people in their jobs and relationships and the logic of the investigator's statement makes perfect sense to them. The elicited agreement that the suspect can tell when others lie is an important part of selling this argument. In essence, the investigator is saying that because the suspect can tell when others are lying through observing behavior, that the investigator also has that ability.
In summary, because at the outset of interrogation an investigator often lacks substantial evidence to prove a suspect's guilt, contemporary interrogation techniques minimize reference to evidence against a suspect. As a result, suspects frequently request to know what the evidence is that proves their guilt. In most instances the investigator will lose credibility, and therefore the ability to obtain a confession, if the available evidence is revealed. Consequently, during an interrogation the investigator must credibly sidestep the suspect's request to see the evidence against them.