Don R. Harris, 66, an economist by training and intelligence officer by profession who worked for the Central Intelligence Agency from 1953 to 1965 and for the Defense Intelligence Agency since 1980, died of cardiac arrest Dec. 6 at Commonwealth Doctors Hospital.

Dr. Harris, who lived in Oakton, received the Intelligence Medal of Merit from the CIA in 1965 and the Meritorious Civilian Service Award from the DIA in 1983.

From 1965 until 1980, he was a private consultant to various private and government agencies. He was an expert on the use of intelligence techniques by state and local law enforcement organizations. He advised a number of police departments and wrote a number of textbooks on the subject.

Dr. Harris was born in Selma, Calif. He graduated from the University of California at Berkeley and later received a doctorate in international economics there. During World War II, he served in the Army's 10th Mountain Division in Alaska and Italy and won the Bronze Star medal.

He moved to the Washington area in 1950. He was an economics analyst at the Brookings Institution until he joined the CIA in 1953. There he was assigned to the Office of National Estimates and served successively as chief of its Far East and West Europe staffs. He also formed and headed the Joint Analysis Group, an effort by the CIA and the Defense Department to develop intelligence estimates for long-range planning.

At the Defense Intelligence Agency, Dr. Harris worked in the directorate for plans and policy.

His marriage to the former Gail Rogers ended in divorce.

Survivors include his wife, Ann Seely Harris of Oakton; three children by his first marriage, Sandra Gail Hart of Cupertino, Calif., Randall R. Harris of San Jose, Calif., and Gillian G. Tufts of Ithaca, N.Y.; three stepchildren, Nancy Seely of San Diego, Gregory Seely of Oakton, and Charles Seely of Mason City, Iowa, and 10 grandchildren.