A leading forensics expert has spoke out, commenting 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, mainly generic versions of the anti-anxiety medications Xanax and Valium, when he died on Tuesday afternoon. Also Two types of sleeping aids, Donormyl and Zopiclone, were found next to Ledger. At least some of the pills apparently had been purchased overseas, but 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 only if a person takes 10-20 or even more at one time. "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. 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 and toxicology tests conducted on Ledger's hair "will tell whether he was a drug abuser." Meanwhile, Dr Maria Gomez of Montefiore Medical Center, told the paper that both Valium and Xanax can when overused or mixed with alcohol, slow breathing so much that it stops altogether. 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.