An autopsy on actor and director Philip Seymour Hoffman has come back inconclusive.
The city medical examiner's office says more testing needs to be done to determine his cause of death.
The news comes as four people were arrested on drug charges Tuesday night.
Sources say they were taken into custody around 8 p.m. as authorities executed search warrants in Greenwich Village.
Sources say police seized about 350 glassine envelopes containing what's believed to be heroin.
Three men and a woman were arrested.
According to the Associated Press, two people close to the Hoffman investigation say a confidential source provided a tip that the suspects may have supplied him with drugs.
Hoffman's body was found Sunday in his West Village apartment.
A needle was in his arm and police found heroin, cocaine and prescription drugs inside the home.
Police believe he may have overdosed but no cause of death has been released yet.
Law enforcement sources say the night before he died Hoffman took out 1,200 in separate withdrawals from a grocery store ATM near his West Village apartment.
Meantime, Broadway theaters will dim their lights tonight in Hoffman's honor.
A private funeral is planned for Friday in Manhattan.