Lynda H. Spering Humphreys, 42, who was found shot to death at her home in Lake Barcroft Sept. 17, was a real estate agent by profession and a volunteer who supported the PTA, the Boy Scouts and community projects.

Fairfax County police said Mrs. Humphreys had been shot by her husband, Marvin W. Humphreys, a Foreign Service officer, and that Mr. Humphreys then took his own life.

A native of Bryn Mawr, Pa., Mrs. Humphreys grew up there, in Bronxville N.Y., and in the Washington area. She attended Bethesda-Chevy Chase High School, the Holton Arms School, and graduated from St. Mary's Junior College in St. Mary's City, Md.

She married in 1957 and accompanied her husband on various asignments abroad, including Vancouver, Palermo, Paris, and several posts in West Germany. Mrs. Humphreys enjoyed her travels and was known for her ability to learn foreign languages and the skill with which she mastered local cuisine.

The family returned to the Washington area in 1976. Mrs. Humphrey became a real estate agent with the Fairmac Realty company, a position she held at the time of her death. She also was active in organizing waterfront activities at Lake Barcroft. She was fond of animals and showed her dogs and cats in Europe.

Survivors include two sons, David, a senior at the Massachusetts Institute of Technology in Cambridge, Mass., and Steven, a junior at Yale University in New Haven, Conn.; her parents, Mr. and Mrs. Howard S. Spering, of Chevy Chase; a sister, Nancy S. Scull, also of Chevy Chase, and a brother, Somers A. Spering of Northridge, Calif.