John M. Provenzano; Longtime L.A. Prosecutor

John M. Provenzano, 66, a key prosecutor in the Los Angeles County district attorney’s office. The retired prosecutor, who had at one time served as chief deputy of the department, became nationally known in 1965 when he prosecuted police over the slaying of a black man, Leonard Deadwyler. Deadwyler had been fatally shot when police pursued and pulled over his car as he was rushing his pregnant wife to the hospital. Johnnie L. Cochran Jr., a lawyer best known recently for successfully defending O. J. Simpson, represented the Deadwyler family. As the case progressed, Provenzano was chronicled in national magazines and newspapers across the country. Born in Huntington, N.Y., Provenzano attended Hamilton College in New York and moved west to attend UCLA Law School. On Wednesday in Palos Verdes Estates of a heart attack.