Investigation reveals who gave powerful anesthetic drug to Michael Jackson

Jackson's personal doctor, Conrad Murray, who was with him when he died June 25 at his rented California home, has been identified in court papers as the subject of a manslaughter investigation.

Murray's lawyers have maintained for weeks that the doctor was simply a witness in Jackson's death and had nothing to do with it.

"Dr. Murray didn't prescribe or administer anything that should have killed Michael Jackson," Murray's lawyer Ed Chernoff said July 6.

Murray's lawyer has specifically said his client never gave Jackson Oxycontin or Demerol, but he hasn't made the same claim about propofol, an anesthetic used to knock patients out for diagnostic tests or surgery that is recommended for use only under strictly controlled conditions.