ET has the latest...

ET confirms the autopsy for HEATH LEDGER, who died earlier today in New York City, will be conducted on Wednesday to find out the cause of death. The results are expected sometime tomorrow afternoon.

EMS officials tell ET that they were called to the scene at 3:26 and arrived only three minutes later. They say that Ledger was in cardiac arrest and had no heartbeat or pulse and wasn't breathing. Medical technicians performed CPR but were unable to bring the young actor back.

It was earlier reported that Heath was found at an apartment inhabited by actress MARY-KATE OLSEN, but the actress' representative tells ET: "She does not own that apartment. She has never owned an apartment in that building."