The short answer is yes. Police officers can lie, deceive, and falsify their true identities to obtain information from a suspect. Undercover sting operations are based on the premise of deception in order to catch criminals. It is a dangerous myth to think police have an ethical duty to tell the truth in all circumstances and in every situation. Many prostitutes still think that if they ask their prospective customer if they’re a cop that will save them from a conviction.
During the course of an investigation an investigator often must rely on duplicity and pretense in an effort to develop evidence against the guilty suspect. Common examples include the use of undercover operatives, hidden surveillance video or “baiting” a cash drawer with extra money. Provided these procedures do not entice a person to commit a crime (entrapment), they are generally acceptable practices. However, courts give greater scrutiny to situations when an investigator knowingly lies to a suspect in an effort to obtain evidence. The courts recognized that deception by law enforcement is often required to solve crimes but also prohibits the police from making false statements to a suspect under certain circumstances.
The landmark court case regulating false statements made to a suspect is the U.S. Supreme Court case of Frazier v. Cupp, 394 U.S. 731, 1969. The case involved the interrogation of a homicide suspect who was falsely told that an accomplice had already implicated the suspect in the killing. This lie persuaded the suspect to confess to the homicide. The Supreme Court ruled that such use of trickery and deceit can be permissible (depending on the totality of circumstances) provided that it does not shock the conscience of the court or community.
The last line is the one where lawyers can argue over the facts and arrive at different conclusions. However, the court has provided examples of “shocking the conscience of the court or community”. Such impermissible conduct includes an investigator lying about his identity and introducing himself as the suspect’s court appointed attorney. Similarly, an investigator who poses as a clergyman in an effort to obtain a confession under that guise would constitute behavior that shocks the conscience of the court or community. Over the last 35 years courts have upheld countless confessions even though the investigator lied to the suspect during an interview or interrogation. In most of these cases the investigator made false statements about being in possession of evidence that implicated the suspect in the crime e.g., eye-witness, fingerprint, DNA, etc.
If you’re questioned by the police concerning a crime, know the police can lie and use deception to obtain evidence against you. Until you’ve spoken with a criminal lawyer, it’s smart to keep your mouth shut and say nothing.