An autopsy on Heath Ledger was inconclusive, and more tests are needed, the medical examiner’s office said today, a day after the 28-year-old actor was found dead with sleeping pills nearby.

It will take about 10 days to complete the investigation, a spokeswoman for the medical examiner, Ellen Borakove, said.

Earlier, police said the death was caused by a possible drug overdose and appeared to be accidental.

Fans left flowers and candles outside the apartment building in Manhattan’s SoHo where the body of the Oscar-nominated star of “Brokeback Mountain” was found.

A stage manager for a Broadway show, Khaled Ali, 41, dropped off a candle on his way to work. He said he and his fellow cast members were devastated by the news of Ledger’s death.

“I felt a connection with him as an actor, as a fellow in the theater community,” he said. “With ‘Brokeback Mountain’ he touched me personally in telling the story of my community. It was very touching.”

Ledger was known for grueling, intense roles that became his trademark after he got his start in teen movies like “10 Things I Hate About You.”

The Australian-born actor was found dead yesterday by his housekeeper and masseuse — lying naked and face-down at the foot of his bed, with prescription sleeping pills nearby, police said.

Ledger split last year with Michelle Williams, who played his wife on the set of “Brokeback Mountain.” The two had a daughter, the now 2-year-old Matilda, and had lived together in Brooklyn’s Boerum Hill neighborhood.

Early today, Ms. Williams and Matilda left Trollhattan, Sweden, where the 27-year-old actress had been shooting scenes for the upcoming film “Mammoth,” a spokesman for film production company Memfis Film, Martin Stromberg, said.

“She received the news at her hotel late last night,” Mr. Stromberg said, adding he had not spoken to the actress after she learned of Ledger’s death.

Ledger was a widely recognized figure in his SoHo neighborhood. Near the entrance to the building housing his loft, about two dozen bouquets and a dozen candles formed a makeshift memorial.

One note said, “I couldn’t find anything bad about you.”