Leonard M. Carpenter, a retired trailer park owner and former Baltimore County sheriff, died Sunday in Orma, W.Va., at the home of his brother after an apparent heart attack. He was 73.

Services for Mr. Carpenter were being held today at the Stump Funeral Home in Arnoldsburg, W.Va.

He was appointed to fill out the term of Sheriff Gilbert L. Deyle, who died in December 1973, but when Mr. Carpenter ran for a full term in the November 1974 elections, he was defeated by Charles H. Hickey Jr.

His wife, the former Constance Simonsen, died in 1986.

He is survived by a daughter, Connie Stonestreet of Little Orleans; his brother, Rex Carpenter of Orma; three sisters, Iva Boggs of Spencer, W.Va., Marion Wood of Arnoldsburg and Ellen Carpenter of Baker, W.Va.; four grandchildren; and four great-grandchildren.