Query: When was Hanssen a spy for Russia/the SU?
Context: On 20 February 2001, the bureau announced that a special agent, Robert Hanssen (born 1944) had been arrested for spying for the Soviet Union and then Russia from 1979 to 2001. He is serving 15 consecutive life sentences without the possibility of parole at ADX Florence, a federal supermax prison near Florence, Colorado.