New York City's Chief Medical Examiner says it's still unclear what killed actor Philip Seymour Hoffman.<br/> <br />A spokesperson for the medical examiner's office said on Wednesday autopsy results are inconclusive and further tests are needed.<br/> <br />No timetable was given as to when those results will be in.<br/> <br />Hoffman was found dead in his Manhattan apartment on Sunday from an apparent heroin overdose.<br/> <br />Police say he had a syringe in his arm and investigators found at least 50 bags of heroin in the apartment.<br/> <br />On Tuesday, police arrested four people on drug charges during a raid at a New York City apartment building.<br/> <br />They're being questioned in connection with narcotics found in Hoffman's home.
