NEW YORK (Reuters) - Actor Heath Ledger died of an accidental overdose of six prescription drugs, with a mix of painkillers, tranquilizers and sleeping aids found in his system, officials said on Wednesday.
A law-enforcement source with knowledge of the case said a formal request for the city medical examiner's records had been filed on Wednesday, seeking to discover who provided the 28-year-old Australian with the lethal combination.
Ledger, renowned for his role as a conflicted gay cowboy in the 2005 movie "Brokeback Mountain," was found dead in his Manhattan apartment on January 22, naked and with several prescription drugs nearby.
"We have concluded that the manner of death is accident, resulting from the abuse of prescription medications," the New York City Medical Examiner's Office said in a statement.
"Mr. Heath Ledger died as the result of acute intoxication by the combined effects of oxycodone, hydrocodone, diazepam, temazepam, alprazolam and doxylamine," the statement said.
His death shocked film fans and fellow actors around the world and added his name to the list of movie stars who died young, like Marilyn Monroe and James Dean.
A spokeswoman for the U.S. Drug Enforcement Administration declined to comment but said the federal agency was committed to identifying any illegally obtained prescription drugs.
Medical experts said it was highly unlikely a single doctor would have prescribed such a mix.
"If someone has an overdose death with that kind of toxicology report, it's usually an indication that they were either doctor-shopping or purchasing medications either on the street or on the Internet," said Andrew Kolodny, a psychiatrist at Maimonides Medical Center in Brooklyn.
The painkillers oxycodone and hydrocodone are opiates, which are dangerous when combined with anti-anxiety medicines like diazepam, alprazolam and temazepam, potentially causing respiratory arrest, doctors said.
Diazepam is sold under the brand name Valium and alprazolam is sold under the name Xanax. Temazepam is also used as a sleep aid and sold under the name Restoril. Doxylamine, a sleep aid and antihistamine, is an active ingredient in a number of over-the-counter medications, including NyQuil.
Ledger had said in recent interviews he was having trouble sleeping during the filming of the latest Batman film "The Dark Knight" in which he plays The Joker, a homicidal maniac. The film is due out in July.
Some published reports also said he was having difficulty dealing with his recent breakup with actress Michelle Williams, and that he badly missed the 2-year-old daughter they had together, Matilda.
The couple met during the filming of "Brokeback Mountain," for which Ledger received an Oscar nomination.
Before and after his relationship with Williams, Ledger had been romantically linked with a number of actresses and models, periodically spotted in exclusive clubs around New York.
Kim Ledger, the actor's father, said the family was humbled by the outpouring of support from fans around the world since his death and asked to be allowed to grieve privately.
"Today's results put an end to speculation, but our son's beautiful spirit and enduring memory will forever remain in our hearts," he said in a statement.
"While no medications were taken in excess, we learned today the combination of doctor-prescribed drugs proved lethal for our boy."
Some of Ledger's other film credits included "The Patriot" in 2000, "Monster's Ball" in 2001 and "I'm Not There" in 2007.