A rolled-up $20 bill found in Heath Ledger's apartment has tested negative for drug residue, police officials told ABC News.
Earlier, investigative sources told ABC News the bill might be coated with what appeared to be the residue of a recreational drug. The way the bill was found -- rolled up -- was the primary reason police had it tested in a lab.
The news that the lab results showed the bill was clean comes as officials attempt to identify substances that may have led to what still appears to be an accidental overdose by the actor Tuesday.
Authorities also revealed to ABC News details about the drugs found in Ledger's apartment. They included multiple prescription drugs (including Ambien, Xanax and Vallium in their generic forms), over-the-counter medications and medications from Europe. The prescription medications were made out in the actor's name and were in the prescription bottles or packets.
A preliminary autopsy completed this morning was unable to determine what killed the actor. His body was found Tuesday in his Soho loft.
The New York City medical examiner's office told ABC News it will conduct additional toxicology and tissue tests that will take from 10 days to two weeks to complete.
According to the medical examiner's office, there are no obvious indicators of what killed the "Brokeback Mountain" star, and nothing to contradict initial police reports that the death was not a suicide.
The initial autopsy did, however, offer clues about the cause of Ledger's death.
The fact that initial tests were inconclusive suggests his death was caused by substances in his system rather than diseased or damaged organs, according to New York-based forensic psychiatrist Dr. Michael Welner, who is not involved with the investigation.
During an autopsy, Welner said, medical examiners are "looking for mechanisms of disease; the diseased heart, diseased lungs." These investigations take less time to complete than toxicological tests, which could reveal effects of drugs and other substances on the body.
A makeshift memorial of flowers and farewell notes was left outside the downtown Manhattan apartment building where the actor died Tuesday, as fans around the world and family members mourned the death of the Australian star.
Ledger, 28, was found naked and face down on the floor of his rented Soho loft Tuesday with several bottles of prescription drugs nearby.
Police told ABC News that the medications may have played a part in the death, which appeared to be accidental.
The death of Ledger stunned his fans and friends. A small display of flowers and candles were set up outside the apartment building along with farewell notes. One message read, "I couldn't find anything bad about you."
The actress Michelle Williams, the mother of Ledger's 2-year-old daughter, Matilda, left Sweden where she was filming a new movie yesterday with their daughter to return to New York. Williams, 27, played Ledger's wife in "Brokeback Mountain." The two were engaged but separated last year.
"She received the news at her hotel late last night," said Martin Stromberg, a spokesman for film production company Memfis Film.
Ledger's body was discovered at 3:31 p.m. by a masseuse who arrived at the apartment for an appointment with him, police sources said. The masseuse was let in by a housekeeper, who then knocked on the door of Ledger's bedroom.