The actor was found dead in the apartment by a friend who had become concerned after being unable to reach him.
The Emergency Medical Service workers, who reached his fourth-floor apartment following an emergency call by the friend, declared him dead on the scene on February 2.
Investigators found a syringe in his arm and an envelope nearby containing what appeared to be heroin.
"We are devastated by the loss of our beloved Phil and appreciate the outpouring of love and support we have received from everyone. This is a tragic and sudden loss and we ask that you respect our privacy during this time of grieving," Hoffman's family said in a statement.
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Hoffman had been struggling with drug addiction problem.
Last year, he even checked into a rehabilitation programme for about 10 days after his dependence on prescription pills resulted in his briefly returning to heroin.
The plastic envelopes near Hoffman's body were stamped with two drug brands. One read Ace of Spades in purple lettering and the other had a red icon of the ace of hearts, according to a law enforcement official.
Narcotics detectives from the New York Police Department were investigating the death.
Hoffman was last seen alive at 8 pm on Saturday. He was expected to pick up his children on Sunday but failed to show up, prompting playwright David Katz and another friend to go to his apartment, where they found him dead, CNN said citing a law enforcement official.