Dennis Adrian Dempsey, 40, a former captain on the Rockville City Police force and a Washington native, died of a heart ailment Jan. 17 at the Aurora Community Hospital in Aurora, Colo.

Mr. Dempsey, who lived in Aurora, a suburb of Denver, grew up in Silver Spring and graduated from Montgomery Blair High School. He attended Montgomery Junior College and the Southern Police Institute at the University of Louisville in Louisville.

In 1964, he joined the Maryland State Police. In 1973, he joined the Rockville force as a captain. In 1977, he moved to Trinidad, Colo., as chief of police. In 1980, he moved to Aurora. At the time of his death he was general manager and vice president of the American Cable Security company.

He was a member of the Good Shepherd Methodist Church and the Hillandale Volunteer Fire Department in Silver Spring;

His marriages to the former Amy Immler and Kathy Claggett ended in divorce.

Survivors include his wife, Diane Dempsey of Aurora; three children by his first marriage, Christopher Jason, Christie Lynn and Mary Ellen, all of Silver Spring; his parents, Charles David and Thelma Louise Dempsey, of Edgewater, Md.; two brothers, Charles Martin Dempsey of Silver Spring, and Michael David Dempsey of Edgewater, and one grandmother, Eunice Dempsey of Rhoadesville, Va.