Former FBI Agent Robert Hanssen, Who Was Convicted of Spying for Russia, Dies in Prison

An artist's depiction of U.S. Attorney Randy Bellows (R) addresses the court during the sentencing of convicted spy Robert Hanssen (C) with his attorney Plato Cacheris (L) at the federal courthouse in Alexandria, Va., on May 10, 2002. William Hennessy, Jr. via AP

WASHINGTON—A former FBI agent who took more than $1.4 million in cash and diamonds to trade secrets with Russia and the former Soviet Union in one of the most notorious spying cases in American history died in prison Monday.

Robert Hanssen, 79, was found unresponsive in his cell at a federal prison in Florence, Colorado, and later pronounced dead, prison officials said.