John Bacon and Melanie Eversley

USA TODAY

The results of an autopsy of Philip Seymour Hoffman's body were inconclusive, and more tests must be conducted to determine what caused his death, a spokesperson for the New York City medical examiner's office said Wednesday.

There is no timetable for completion of toxicology and other tests, spokesperson Julie Bolcer told USA TODAY.

The body of the Academy Award-winning actor, 46, was found Sunday on the bathroom floor of his New York apartment with a syringe in his left arm and bags of what appeared to be heroin inside the apartment. Those items were being tested. Police will only say the investigation is continuing.

Hoffman had publicly acknowledged his struggles with drug addiction.

Four people were taken into custody in Manhattan and questioned in connection to potentially selling drugs to the actor, local media and the Associated Press are reporting.

The Associated Press also reported Wednesday night that at least one of the four arrested had Hoffman's cellphone number. The news organization based the news on word from two law enforcement officials who requested anonymity because they are not authorized to discuss evidence in an ongoing investigation.

In the hours before his death, Hoffman reportedly made several withdrawals totaling more than $1,000 from a bank machine near his apartment.

Detective Brian Sessa told USA TODAY that the four were taken into custody during the execution of a search warrant, but he declined to link the case to the Hoffman investigation. Drugs were found at the location where the four were apprehended, Sessa said. The New York Times reported that 350 bags of heroin were found.

A private funeral for Hoffman will be held Friday in New York City. Plans also are underway for a memorial service in the city later this month, Hoffman representative Karen Samfilippo said.

Hoffman won an Oscar for his portrayal of Truman Capote in the 2005 film Capote. Hoffman, who was last seen alive Saturday night, has three children — Cooper, 10, Tallulah 7, and Willa, 5 — with costume designer Mimi O'Donnell.