Jack Gregory Downing was born on Oct. 21, 1940, in Honolulu and raised by his mother, Benita (Harding) Downing, a couture buyer for Neiman Marcus. His father, John, was a Navy officer who was killed at sea in the Pacific in the early days of World War II, when Jack was a year old. After his father’s death, his mother moved with Jack and his sister to his maternal grandparents’ home in Texas, where he grew up.
He attended the Hill School in Pottstown, Penn., as a boarder and then Harvard, where he focused on Chinese language and history and Asian studies, graduating in 1962. He served four years in the Marines as an infantry lieutenant in a rifle company in Vietnam. He was discharged on a Friday in 1967 and sworn in as a C.I.A. officer the following Monday.
He went on to head the agency’s East Asia Division, serve as a special assistant to Adm. Stansfield Turner when he was C.I.A. director during the Carter administration, and take over as station chief in Kuala Lumpur, Malaysia.
In the early 1980s, Mr. Downing and Tony Mendez, the agency’s master of disguises, devised a graduate course for spies to enable them to circulate undetected in foreign capitals.
Mr. Downing, having learned Russian, was Moscow station chief from 1986 to 1989, where he foiled K.G.B. plots to plant Russian double agents. He was put in charge after most of the Russians working for the agency had been betrayed to the K.G.B. by Mr. Ames, a C.I.A. officer in Washington. Some of the agents were executed. Mr. Ames was convicted of espionage in 1994 and is serving a life sentence in prison.
Between stints at the agency, Mr. Downing was vice president of an information systems and consulting firm.
In addition to his son, John, he is survived by his wife, Suzanne (Leisenring) Downing; his daughter, Wendy Rogers Downing; his sister, Roberta Lee Jurek; and four grandchildren.