Robert Hansen, The former fbi agent US officials said the spy who became what the bureau describes as the most damaging in its history was found dead in his jail cell on Monday.
Hansen, 79, was sentenced to life in prison in 2002 after pleading guilty to spying for the Soviet Union and later Russia for more than 20 years.
The Bureau of Prisons said in a statement that prison staff initiated life-saving measures after finding Hansen unresponsive on Monday morning, but were not successful. It did not specify the cause of death.
Hansen joined FBI Began selling more in 1976 classified information In the Soviet Union in 1985, according to the FBI’s website.
By the time of his arrest in 2001, he had been paid more than $1.4 million in cash, bank funds and diamonds in exchange for compromising multiple human sources, intelligence techniques and classified US documents, the FBI’s website says.
FBI investigators worked for years trying to identify the spy in their ranks. In the weeks following his February 2001 arrest, approximately 300 workers working on investigation and surveillance of Hansen, according to the FBI.
The FBI says an arrest squad took Hansen into custody after catching him making a “dead drop” of classified material in a park in suburban Virginia.
He was serving his life sentence at a maximum security facility in Colorado.