You are a homicide investigator and are interrogating someone you believe picked up a nine year old girl in a shopping mall, molested her and murdered her. He is a registered sex offender. He was in the area when the crimes occurred. Although he does not have any significant prior convictions for violent crime, you believe there are no other possible suspects who had the means, opportunity and motive. You have some circumstantial evidence because he was seen on video following the child at the mall, but you have no solid physical evidence. (Remember to take my criminal law and evidence classes for a better understanding of the differences between these two types of evidence.) You’re going to need him to admit the crimes to prove up your case.
After several hours of getting nowhere, you have an idea. You ask one of your colleagues to come into the interrogation room and with a file folder and a false story. Your fellow detective quickly agrees. She barges into the room, tosses the folder on the table and tells the suspect that the medical examiner lifted his prints from the victim’s body. You immediately tell him that he lost his chance to confess because now he is facing the death penalty. He quickly responds that he will say anything you want him to if the death penalty is taken off the table.
How do you respond? Do you have any ethical issues with lying to the suspect about the existence of his fingerprints on the body? Does it matter if you had already Mirandized him? Would you tell the prosecutor assigned to the case what you did to obtain his admissions?