Robert Hanssen, FBI agent who spied for Russia, found dead in prison

FILE PHOTO: Robert Hanssen, a former FBI agent deemed a traitor by the government Undated handout photo of former FBI agent Robert Hanssen. QUALITY FROM SOURCE REUTERS/FBI/Handout

WASHINGTON (Reuters) - Robert Hanssen, the former FBI agent turned spy whom the bureau describes as the most damaging in its history, was found dead in his prison cell on Monday, U.S. authorities said.

Hanssen, 79, was sentenced in 2002 to life in prison after pleading guilty to spying for the Soviet Union and later Russia for over 20 years.