William L. Mustin Sr., a retired Baltimore police officer and decorated World War II veteran, died yesterday at his daughter's home in Pasadena of a heart attack. He was 75.

Services for Mr. Mustin were being held today at the McCulley Funeral Home, Mountain and Tick Neck roads, Pasadena.

He is survived by his wife of 55 years, the former Isabelle Shue; three children, William L. Mustin Jr. of Glen Burnie, Lalonny R. Baumes of Pasadena and Kim D. Nye of Riviera Beach; nine grandchildren; and four great-grandchildren.

The family suggests memorial contributions to the American Cancer Society.