Heath Ledger's death: 'accidental overdose unlikely'

A leading forensics expert said today that it was unlikely actor Heath Ledge could have accidentally overdosed on the prescription pills found in his New York apartment.

The Brokeback Mountain star reportedly had six types of drugs prescribed in his name in his home - mainly generic versions of the anti- anxiety medications Xanax and Valium - when he died on Tuesday afternoon, law sources said.

Two types of sleeping aids, Donormyl and Zopiclone, were found next to Ledger, whose cause of death remains under review by authorities.

At least some of the pills apparently had been purchased overseas.

Ledger recently returned to the US from London.

Dr Michael Baden said: "The pills generally have a large safety margin.

"You just don't take one extra pill and die."

Baden told the New York Post that fatal overdoses of the pills can occur, but typically only if a person takes 10, 20 or even more at one time - in excess of the recommended dosage.

"We don't see very many deaths from the common sleeping pills," said Baden, chief forensic pathologist for the New York State Police, and the former chief medical examiner of New York City.

Baden also told the newspaper that if someone is prescribed pills under a wide variety of brand names - as Ledger was - for a single purpose such as sleep, it could indicate that person was abusing the drugs.

Prescription pills are "probably abused more than illegal drugs," Baden added.

Baden also told the New York Daily News that toxicology tests conducted on Ledger's hair "will tell whether he was a drug abuser."

Meanwhile, Dr Maria Gomez of Montefiore Medical Center [sic], told the paper that both Valium and Xanax - in a powerful class of tranquilizers called benzodiazepines - can, when overused or mixed with alcohol, slow breathing so much that it stops altogether.

Sleeping aids could intensify those effects, said Dr Gerard Addonizio, a clinical psychiatry professor at Weill Medical College of Cornell University.

It comes amid news an autopsy on the body of the 28-year-old Australian actor performed on Wednesday was found to be inconclusive.

It will take about 10 days to determine the cause of death, a spokeswoman for New York's medical examiner said.

"We have to do additional testing which will include toxicology and tissue testing," the spokeswoman said.