Maude Emily Lyles, a career federal employee and a lifelong resident of Alexandria and the District of Columbia, was found dead of a heart attack Friday in her Van Ness Street apartment. She was 70.

Miss Lyles was born in Milton, Mass., and moved to the Washington area as an infant. She studied at a business school in the District and subsequently held several jobs with various federal officials during the New Deal era of the Franklin Roosevelt Administration.

During the Truman administration, Miss Lyle worked for the Hoover Commission that had been formed to reorganize the federal government. From 1952 until her retirement in 1966, she worked for the National Historical Publications Commission, where she assistant to the commission's executive director, the late Dr. Philip M. Hamer.

Following retirement, Miss Lyles continued to work with Dr. Hamer as an editorial assistant in the preparation of the first volume of "The Papers of Henry laurens," a delegate to the Continental Congress from South Carolina.

Miss Lyles was an active member of the Washington chapter of the English Speaking Union, an organization formed to promote cultural and social ties between the United States and Great Britain.

Miss Lyles is survived by three cousins, Helen Dubois, Lorraine Kordiluk and Evelyn Daverin, all of Pittsfield, Mass.