Robert Hanssen, a former F.B.I. agent who was sentenced to life in prison in 2002 for spying for Moscow during and after the Cold War in one of the most damaging espionage cases in American history, was found dead in his cell in a federal prison in Colorado on Monday, the Federal Bureau of Prisons said. The bureau said in a statement that Mr. Hanssen was found unresponsive at the United States Penitentiary Florence in Colorado just before 7 a.m. He was pronounced dead after lifesaving efforts by emergency medical workers. This is a developing story.

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Persons: Robert Hanssen, Hanssen Organizations: Federal Bureau of Prisons, United, Penitentiary Locations: Moscow, Colorado, Penitentiary Florence