ABC News has learned that the autopsy of Michael Jackson found the powerful anesthetic propofol, as well as several prescription drugs, in his system, and law enforcement sources say that investigators believe their final report will list the propofol as a "contributing factor" in his death.
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.
Murray, who was hired to monitor the entertainer for his planned "This Is It" tour, was called to Jackson's house June 24 and was the person who found him unconscious, not breathing in bed the next day.
Murray has been widely criticized by medical professionals for waiting more than 30 minutes to call 911 and for performing CPR on a bed instead of a hard surface, but he has continually denied giving Jackson any drug that could have killed him.
He has been secluded at his Las Vegas home and reportedly goes out with a security detail due to death threats.
Late today, The Associated Press reported that a law enforcement official said investigators believed Murray administered the shot of propofol that would end Jackson's life.
Chernoff declined to comment on the report, saying only, "We will not be commenting on rumors, innuendo or unnamed sources."
Cherilyn Lee, a registered nurse and nutritionist who worked for Jackson, said the singer begged her to give him propofol in the days before his death. She refused to help him obtain it.
Lee told ABC News the pop star had often complained of not being able to sleep more than a few hours at a time and wanted propofol to ease his insomnia.
"The problem with you telling me you want to be knocked out," Lee said she told him, is "you might not wake up the next morning. You don't want that."
When investigators searched Murray's Texas office earlier this month, among the items seized were a vial containing 27 tablets of the weight loss drug phentermine, a vial containing a tablet of the muscle relaxant clonazepam, a photocopy picture of Murray, Rolodex cards, public storage receipts, and a receipt for a "Cricket" phone, according to the search warrant.
Other items seized from his storage unit, according to the court records, included two computer hard drives and a "Texas Department of Public Safety controlled substance registration." Authorities also obtained a suspension notice from a Houston hospital.
The search warrants specifically directed officers to "seize and examine all items, including but not limited to, billing records, medication orders, transport receipts, billing receipts, medical records and computerized medical records, for implements and instruments used in the commission of a crime."