A toxicology report released Wednesday says Heath Ledger died from an accidental overdose.  He was found dead in his apartment two weeks ago. A professor at the Medical University of South Carolina’s College of Pharmacy says Ledger was taking three different drugs used to treat the same symptom.

“He may not have realized the medicines were in the same families, doing the same things,” said Dr. Wayne Weart, College of Pharmacy.

The report listed five drugs that were found in Ledger’s toxicology. Valium, Xanax and Restoril were found in his blood. They were all prescribed to treat anxiety, sleep disorders and panic attacks. While Oxycontin is an opiate in the same class as Methadone and Morphine, drugs used to treat pain. Unisom, an over the counter medicine used to induce sleep, was also found in Ledger’s system. All were central nervous depressants.

The medical examiner's report also listed Hydrocodone, which is another pain medication in the opiate family.  Weart says two opiates would not be prescribed together ordinarily.

He added that even recommended doses of the individual drugs, when combined, is enough to kill a healthy human being. Previous reports indicated Ledger was suffering from pneumonia, which causes patients to struggle with breathing. These medications would have only exacerbated this problem.

“He probably just quit breathing,” Dr. Weart said. 

Ledger had been working hard, playing the Joker in the new Batman movie and filming the Bob Dylan biopic.

In a November interview he said he was exhausted, couldn't sleep and had taken Ambien.

Now back in Australia, his father said that while the medications were not taken in excess, the combination proved lethal. Experts say that should serve as a warning to the millions of others who take the same drugs.

Ledger's former partner Michelle Williams and their two-year-old daughter Matilda are now in Australia where Ledger will be buried in a private ceremony, remembered both for the tremendous talent he showed in movies like Brokeback Mountain: and for what his father called his beautiful spirit.