On this day, Feb. 18, in 2001, FBI agent Robert Hanssen was arrested for spying for the Soviet Union and Russia in what is possibly the worst intelligence breach in U.S. history.
Hanssen was taken into custody minutes after leaving a package of highly classified information at a "dead drop" site under a wooden footbridge in Vienna, Va.
Hanssen, a counterintelligence expert and the bureau's liaison to the State Department, was in a key position to slip secrets to his handlers.
Hanssen sold the secrets for $1.4 million in cash and diamonds. He shared details about spy technology and how the U.S. would react to a Soviet nuclear attack.
He was sentenced to life and is being held in the Supermax prison in Colorado.