Grace Elizabeth Johnson, 79, a retired committee aide and investigator on Capitol Hill, died of cardiac arrest Monday at the infirmary of Thomas House in Washington, where she lived.

Mrs. Johnson, who was born in Tazewell, Va., taught at Radford College while studying there and also studied at the University of Virginia. She was married to Chase Atkins, who died many years ago. Following his death, she used her maiden name.

For some years, she lived in Richmond and she and her mother, Mrs. David R. Johnson, acted as hostesses for Gov. George C. Peery during a period when Mrs. Peery was ill.

During World War II, Mrs. Johnson moved to Washington and went to work for the Army Air Force at the Pentagon. In 1944, she took a job on the staff of the late Sen. Carter Glass (D-Va.).

She next was appointed chief clerk of the subcommittee on privileges and elections of the Senate Rules Committee. This is the body to which questions concerning the election and conduct of senators are referred. During Mrs. Johnson's tenure as chief clerk, the committee made inquiries into the conduct of Sen. Theodore Bilbo (D-Miss.), Sen. Dennis Chavez (D-N.M.) and Sen. Joseph R. McCarthy (R-Wis.), who based his career on exploitation of the anticommunist hysteria of the early 1950s and who was censured by the Senate.

Mrs. Johnson later went to work as an investigator for Sen. Carl Hayden (D-Ariz.), chairman of the Senate Appropriations Committee. The committee sent Mrs. Johnson and another woman employe on an around-the-world trip to investigate operations of the old U.S. Information Agency. Her own behavior on this assignment led to controversial news stories and Mrs. Johnson retired in 1957.

In later years, she spent considerable time in efforts to justify her conduct.

Mrs. Johnson's survivors include a sister, Mrs. Charles Blaine of Georgetown, Ohio.