A black motorist who died following a scuffle with two white police officers died of a heart attack brought on by a cocaine overdose, the Philadelphia medical examiner said.

But the investigation by the city and FBI into allegations the officers used excessive force on the man will continue, authorities said Saturday.An autopsy revealed that Michael Grant, 35, ingested a fatal dose of cocaine shortly before police pulled him over early Thursday for making an illegal U-turn, said Medical Examiner Haresh Mirchandani.

Grant, a freelance photographer and father of three, also suffered several blows to the forehead and various cuts and bruises on his body, Mirchandani said. But he said the autopsy "conclusively showed" that none of those blows could have caused Grant's death.

The autopsy also showed that Grant had a cocaine level of .113 mg per hundred in his blood, more than twice the level necessary to cause death, Mirchandani said.