A Bucks County man has admitted causing a crash that killed a Philadelphia police officer nearly three years ago. 44-year-old William Foster of Bristol Township pleaded guilty Monday to third degree murder in the death of Sergeant Timothy Simpson, who was 46 at the time. He was fleeing from police after a drug deal when he sped through a red light and struck and killed Sergeant Simpson in November of 2008, at Aramingo and Allegheny Avenues in the Port Richmond section. Police say Foster had gone into the city for the sole purpose of buying drugs, and he should not have been driving because his license was suspended. They found three bags of heroin in his possession after the crash. A Philadelphia judge gave him 19 to 40 years in state prison.