Can Undercover Officers Pose as Cellmates to Elicit Incriminating Statements?

At what point in a criminal investigation may law enforcement officers no longer use the "Perkins technique?" In Illinois v. Perkins, the U.S. Supreme Court held that statements deliberately elicited by an undercover officer posing as the defendant's cellmate were not inadmissible under Miranda, even though no warnings had been given. Rationale: If the prisoner is [...]