Robert Hanssen, F.B.I. Agent Exposed as Spy for Moscow, Dies at 79
New York Times
He was sentenced to life in prison in 2002, bringing to a close one of the most lurid and damaging espionage cases in American history. His body was found in his cell.
https://www.nytimes.com/2023/06/05/us/robert-hanssen-spy-dead.html