Based on the state in which Philip Seymour Hoffman was found Sunday morning, it's not unreasonable to surmise that his death was caused by a heroin overdose. But three days later, results of his autopsy have been ruled "inconclusive."

USA Today reports that more tests will have to be performed, but that investigators are not working under any specific timetable.

Police launched an aggressive search for the dealers who sold Hoffman the (assumed) fatal dose of smack, and arrested four after raiding an apartment on Mott Street last night. According to TMZ, Hoffman would buy large quantities of the drug at a time, though occasionally he'd run out and have to purchase from a secondary dealer who sold "cheap shit heroin."

The celebrity gossip site also reports that Hoffman confided to his dealer that he was desperate to kick the habit, that he always seemed like a "man on a mission," and that he never engaged in small talk. "Hoffman always looked unhappy," the site says.

The stepdaughter of Robert Vineberg, one of the men arrested last night, acknowledged to the Post that her father dealt drugs to Hoffman, but added ominously that “he had nothing to do with what killed him.” She declined to offer further details about the deal, but said that Hoffman and her stepfather, a musician, had become friends through movies. Had Hoffman come to Vineberg, his daughter said, he would have tried to help him.

“He said, ‘If he would have come to me, I would have told him to slow down, and if you’re going to do something, make sure you have someone with you.’”

The details of the late actor's funeral are understandably being kept private, but a candlelight vigil will be held tonight outside of LAByrinth Theater at 155 Bank Street.