He was seen as one of the biggest outcasts across the Atlantic. Double agent Robert Hanssen, at the heart of one of the most disastrous spy cases for the United States, died on Monday June 5 at the age of 79 in the prison where he had been incarcerated since 2002, announced the American prison services. .

A federal counterintelligence officer, he had sold himself out to the Soviets during the Cold War and delivered some of America’s best-kept secrets of the 1980s and 1990s to Moscow in exchange for $1.4 million and of diamonds. Robert Hanssen was “the most harmful spy in the history of the FBI”, according to the Federal Police website.

He was found unconscious on Monday morning in his cell at the maximum security prison in Florence, Colorado, where he was serving a life sentence. Efforts to resuscitate him were unsuccessful, according to a statement from the Federal Bureau of Prisons.

After starting out with the Chicago police, Robert Hanssen was recruited by the FBI in 1976. A few years later, he joined the counterintelligence section of the New York bureau, responsible for tracking down Russian spies on the American soil and to recruit Soviet diplomats to the United Nations.

Taking advantage of this key post, he had quickly offered his assistance to the intelligence services of the USSR, operating discreetly under the alias “Ramon Garcia” without his handlers knowing his true identity.

Alternating posts in New York and Washington, he delivered to the Soviets and then to the Russians some 6,000 pages of documents, including military plans, counterintelligence software and the names of several double agents operating for the United States.

Although the FBI quickly became aware of the existence of a mole in its services, it remained unsuspected for a long time. Married, father of six children, he lived without being noticed, while maintaining close ties with the Catholic elite of the capital.

He was finally implicated in 2000 by a defecting Russian. Placed under surveillance, he was arrested in 2001 as he prepared to file secret documents for Russian agents in a park in Virginia.

Robert Hanssen avoided the death penalty by agreeing to cooperate with investigators. Admitting to having acted out of greed, he underwent 200 hours of interrogation. In 2002, he was sentenced to life in prison without the possibility of early release.