Brian Kelley, a Vienna resident and former CIA senior counterintelligence case officer, poses in February on a bridge in Foxstone Park, where convicted spy Robert Hanssen passed classified documents to Russian operatives. For nearly four years, Kelley was investigated by the FBI for espionage that later was tied to Hanssen. (Shamus Ian Fatzinger)

Kelley died in his sleep Sept. 19 in Vienna, according to this obituary by The Post’s T. Rees Shapiro. He was 68 and suffered from a heart ailment, his wife said.

After he was cleared in the Hanssen affair, Kelley continued to work as a consultant to the U.S. intelligence community, warning of the dangers of focusing on “the wrong man.” In February, on the 10th anniversary of Hanssen’s arrest, Kelley said he had nearly completed a book about the case and its impact on him and his family.

His wife, Patricia McCarthy Kelley, told The New York Times that “it was his lifelong journey to teach people, so hopefully this never happens again.”