Robert Hanssen, an FBI agent-turned-Russian mole was found dead in his prison cell, earlier today.
Hanssen, described as one of the most damaging spies in US history, was discovered unresponsive at a maximum-security facility in Florence, Colorado.
He was sentenced in 2002 to life in prison for espionage.
Hanssen received more than $1.4 million in cash, diamonds, and money paid into Russian accounts. Three hundred agents worked on his case.
Because of his counterintelligence role, he had access to classified information and in 1985 he started his criminal activity, sending material to Russia and the former Soviet Union.
According to the FBI, Hanssen compromised numerous human sources, counterintelligence techniques, investigations, dozens of classified US government documents, and technical operations.