Heyward M. Braddock, 79, a personnel investigator with the U.S. Civil Service Commission for 28 years until retiring in 1965, and a retired colonel in the Air Force reserves, died Monday at his home in Arlington after a heart attack.

Mr. Braddock came to Washington in the early 1930s and worked as a clerk for several federal agencies before joining the Civil Service Commission in 1937.

Mr. Braddock joined the old Army Air Corps reserves in 1924. He was called to active duty during World War II and served in England. He was recalled to active duty during the Korean conflict, as a criminal investigator with the Office of Special Investigations. He retired from the reserves in 1961.

He was a Mason and member of the Glebe Lodge No. 181 in Arlington. He also was a member of Reserve and Retired Officers associations, the Military Order of World Wars, the American Legion, and the Sons of the American Revolution.

Mr. Braddock was a native of Crescent City, Fla., and a 1939 graduate of American University.

Survivors include his wife, Minnie S., of Arlington; a son, William, of Decatur, Ala.; two brothers, Elbert C., of St. Petersburg, Fla., and Gerald M., of Crescent City, and three grandchildren.