Can the police put an undercover officer or an informant inside the jail cell with you to record what you say about a crime?
The answer is Yes. There are three cases you need to know about to see why. First everybody knows about the Miranda case – if you are in custody and the police are interrogating you, that is making statements or questions designed to elicit an incriminating response, you have the right to remain silent – that is not incriminate yourself (Fifth Amendment) and you have the right to an attorney present if you proceed with questioning (Sixth Amendment).
What if the Detectives talk to you, show you photos, show pictures of a victim who was shot, tell you that they are investigating a homicide, whether recent or old, and then put you back in the tank at the police station?
Under the case of Illinois v. Perkins, they can put an undercover officer or an informant in your cell asking about what you are there for and recording your answers. Why? Because Miranda is designed to prevent coercion from Police – if you don’t think you are talking to the Police there is no coercion so they can deceive you.

