After an autopsy of actor Heath Ledger’s body returned no results on the cause of his death, police said yesterday that laboratory tests found no drug residue on a rolled-up $20 bill found in his apartment.

A spokeswoman for the medical examiner, Ellen Borakove, said the autopsy was “inconclusive,” and that new toxicology and tissue tests would take a minimum of 10 days to determine how he died.

Police said earlier yesterday that a rolled-up bill found in Ledger’s apartment was being sent to the police crime lab for testing, noting that such bills sometimes indicate drug use.

Police officials said no illegal drugs were found in the apartment, but they have said a mix of both prescription and over-thecounter pills, including sleeping aids and anti-anxiety medication, were found in bottles and blister packs in Ledger’s bedroom and bathroom.

As more details emerged yesterday about Ledger’s last hours, police officials said they were speaking with witnesses and reviewing evidence, but had lessened the “intensity” of the investigation after foul play had been ruled out. “This is not a murder investigation,” a police official said.

The official said the women who found Ledger’s body — a housekeeper, Teresa Solomon, and a masseuse, Diana Wolozin — have been cooperating with police. The police said Ms. Solomon and Ms. Wolozin had given them the following details of the discovery of the body:

• Ms. Solomon arrived at the apartment at about 12:30 p.m., and let herself in with her key. As she was cleaning, she noticed Ledger’s bedroom door was closed.

• At about 1 p.m., needing to change a light bulb in the bathroom, Ms. Solomon said she knocked on the door and let herself into his bedroom. Ms. Solomon observed Ledger sleeping on his stomach in his bed with the sheets pulled up to his shoulders. She said he was snoring.

• At 2:45 p.m., Ms. Wolozin arrived for a 3 p.m. massage appointment that Ledger had previously scheduled. When Ledger did not emerge from his room at the appointed time, Ms. Wolozin called him on his cell phone to wake him up from outside of his bedroom, but he did not answer. She then knocked on the door and entered the room and began setting up her massage table.

• A few minutes later, she attempted to wake Ledger, calling his name twice. Ms. Wolozin then approached the bed and shook the actor. Police said Ms. Wolozin told them she noticed his body was cold to the touch, and she also said she believed he was unconscious.

• She then used Ledger’s cell phone to call the actress Mary Kate Olsen, telling police that she believed the Ms. Olsen and Ledger were good friends, and that Ms. Olsen would be able to give her guidance. Ms. Olsen told Ms. Wolozin she would send private security guards to help, according to the account.

• Ms. Wolozin then checked Ledger’s body again, this time coming to the conclusion he could be dead. She quickly called Ms. Olson for a second time and informed her she was calling 911. The call was placed at 3:26 p.m., and a 911 operator guided Ms. Wolozin through CPR, police said.

• Paramedics and a security guard arrived moments later, at 3:33 p.m. They moved Ledger’s body to the floor so that they could properly perform CPR and use a defibrillator, but they were unable to revive him, police said. He was pronounced dead at 3:36 p.m. A total of three security guards, identified as William Durney, Dean Walter, and Dale Araten, responded to Ledger’s home, police sources said.

Police sources said detectives who responded to the scene said the body showed signs that Ledger had been “dead for some time.”

Police officials said it was possible that detectives might investigate how Ledger had obtained the prescription medication and from whom, but would not comment on whether detectives would actually take those steps. Police have said there was no evidence that the death was a suicide, and no evidence of alcohol use.

As speculation has swirled through press and broadcast outlets around the globe, the actor’s family and friends have urged the public to wait for the completion of the police investigation. Ledger had split last year with his companion, Michelle Williams, who played his wife in the critically acclaimed movie “Brokeback Mountain.”

In recent months following the breakup, Ledger had complained of rising stress after playing several difficult roles, including Bob Dylan in “I’m Not There” and the Joker character in the sequel to “Batman Begins.”

He also talked about having difficulty relaxing and an increased reliance on sleeping pills.