An autopsy of Philip Seymour Hoffman's body was inconclusive, and the determination of the official cause of death will have to wait for additional testing, the New York City's medical examiner's office said Wednesday.
"Our examination has been concluded but the results are inconclusive," spokeswoman Julie Bolcer told the Los Angeles Times. "We are awaiting results and additional studies."
Bolcer said there was no time frame available for when the tests would be completed.
Police have said Hoffman appeared to die from a drug overdose, but the exact cause will be determined by toxicology tests.
Hoffman, 46, was found dead Sunday with a needle in his arm in the bathroom of his West Village apartment, police said. At least 50 packets, some containing heroin, were found in his apartment along with unused syringes and a charred spoon, police said. Various prescription medications, including a drug used to treat heroin addiction, a blood-pressure medication and a muscle relaxant, were also found at the scene.
Hoffman had publicly acknowledged abusing drugs and told CBS' "60 Minutes" in 2006 that had he used "anything I could get my hands on" before getting clean at age 22.
In interviews last year Hoffman said he had relapsed, had developed a heroin problem and had gone to rehabilitation for a time.
His death came amid rising concern around the region about a powerful drug hybrid — a mixture of heroin and fentanyl, a synthetic form of morphine — that has been linked to deaths in other states, including 22 deaths within a week last month in western Pennsylvania.
But the drug found at Hoffman's apartment tested negative for fentanyl, a police official said.
Four people have been arrested on drug charges in New York after Hoffman's death, though whether the suspects were involved with the actor remained unclear on Wednesday.
Police refused to discuss any relationship between the arrests and Hoffman's death over the weekend.
But local media reports, based on unnamed police sources, said the arrests came after raids based on information gathered from the Hoffman investigation and that authorities were looking at whether there were any connections between those arrested and Hoffman.
Several reports said police making the arrests had recovered heroin packaged in the same way as the drugs found in Hoffman's apartment. Dealers often brand their products, and in this case the drugs carried the brands identifying them as Ace of Spades or Ace of Hearts.