PHILADELPHIA — A Philadelphia policeman shot while on duty four decades ago died of his injuries this week, raising the possibility of a homicide charge against a man who already served a prison sentence for the shooting, authorities said. Walter T. Barclay, a rookie officer, was gunned down Nov. 27, 1966, while trying to stop the burglary of a beauty shop in the city's East Oak Lane section. Barclay, who was left a paraplegic, died Sunday at age 64. William J. Barnes, now 71, was sentenced to a 10- to 20-year term in the shooting. Chief Inspector of Detectives Joseph...