While attending graduate school at Duke University, he left to join the CIA in 1962, where he worked for over four decades.
In the 1980s, he was a national intelligence officer for Russia and Eastern Europe and became congressional liaison, serving under two CIA directors.
His term ended soon after the Benjamin Netanyahu government became dissatisfied with his role and an Israeli paper outed his identity as CIA station chief.
After retiring in 2005, he continued as a consultant and CIA's representative to the Interagency Working Group on Nazi War Crimes.
Former CIA directors Michael V. Hayden and George Tenet issued statements praising him as "truly exceptional" and "indispensable."