#Robert Hanssen, most damaging spy in FBI history, found dead in prison cell

Robert Hanssen, an FBI agent who spied for Russia and the former Soviet Union, was found dead in his prison cell Monday, according to a release obtained by CBS News. 

Hanssen was found unresponsive at the federal correctional complex in Florence, Colo., pronounced dead after life-saving measures were attempted, according to the release from Kristie Breshears, the Federal Bureau of Prisons (FBOP) director of communications. 

“Staff requested emergency medical services and life-saving efforts continued. The inmate was subsequently pronounced dead by outside emergency medical personnel,” the release reads.

The 79-year-old had been in custody at the ADX Florence complex for more than two decades, since 2002. He pleaded guilty to 15 counts of espionage in 2001 and was sentenced to life in prison without parole.

The FBI’s site calls Hanssen “the most damaging spy in Bureau history.” Under an alias, he’d provided Russians with highly classified national security information “in exchange for more than $1.4 million in cash, bank funds, and diamonds.” His espionage activities dated to 1985, according to the FBI page.

The Monday release shared by CBS News did not include information about a cause of death for Hanssen. Breshears noted that no staff or inmates were injured, and the FBI was alerted of the death. The Hill has reached out to the FBOP for more.