The results of an autopsy on Oscar-winning actor Philip Seymour Hoffman's body were inconclusive, and further tests have been ordered, the New York medical examiner's office said this evening.
A spokeswoman said that pathologists had not yet reached a conclusion on the cause and manner of the death of the 46-year-old.
His body was found in his New York home on Sunday.
Police, who suspect a drugs overdose as the cause of death, said Hoffman was found with a needle in his arm, and there were 50 envelopes of heroin, syringes and other pills in the apartment.
The sudden death of the father of three young children, hailed by many as the finest character actor of his generation, has shocked Hollywood and devastated his family.
But the medical examiner's office is awaiting the results of further tests and gave no time frame for when they might be available other than indicating it might take several more days.
The spokeswoman refused to comment in detail on specific tests but it is not uncommon for further tissue and toxicology reports to be ordered in such cases.
In a career spanning more than 20 years and 50 films, Hoffman mesmerised filmgoers with his portrayal of some of the most repellent and yet electrifying characters of the silver screen.
US media have reported that his funeral will take place on Friday morning at the St Ignatius of Loyola Catholic church on Park Avenue, preceded by a private wake tomorrow.
The same church was the scene of the 1994 funeral of Jackie Kennedy Onassis, the wife of assassinated US president John F Kennedy.
Subdued fans have laid roses, photographs and beer outside the apartment at 35 Bethune Street where he was found dead, close to the home of his three children and estranged girlfriend Mimi O'Donnell.
Police investigating Hoffman's death arrested three men and a woman with a large amount of heroin in Lower Manhattan yesterday.
The three men, aged 22, 48 and 57, and the woman, 22, were all detained on drug-related charges, a police spokesman said.
According to US media, police said heroin found in Hoffman's apartment did not contain fentanyl, a powerful additive that has been tied to 22 recent fatal overdoses in Pennsylvania.
Hoffman had admitted in May to falling off the wagon more than a year previously, after two decades of sobriety, starting with prescription pills and escalating to heroin use.
The actor was last seen on Saturday and O'Donnell raised the alarm when he failed to show up to see his children on Sunday.
She was quoted by US media as saying he was high when she last saw him and spoke to him on Saturday.