Investigators zeroed in on the four after a tipster, responding to publicity about Hoffman's death, told police he had seen Hoffman at the lower Manhattan apartment building where they were arrested on Tuesday and he believed that's where Hoffman got the heroin, the officials said.
After obtaining search warrants for two apartments in the building, police found about 350 packets of heroin in one of them, the officials said.
Some of the packets found in Hoffman's apartment were variously stamped with the ace of hearts and others with the ace of spades. Those found in the building where the arrests occurred had different brand names, including Black List and Panda, the officials said.
The officials weren't authorised to speak about evidence in the ongoing investigation of the death and spoke to The Associated Press on the condition of anonymity.
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Hoffman, 46, was found dead Sunday with a needle in his arm, and tests found heroin in samples from at least 50 packets in his apartment in Manhattan's Greenwich Village, law enforcement officials have said.
The four suspects face charges of criminal possession of a controlled substance. Two also face charges of criminal possession of drug paraphernalia.