here's what wikipedia has on it:
According to the New York City Police Department, Ledger was found dead in his apartment in the SoHo neighborhood of Manhattan on January 22, 2008.[20][21]
'The New York Times reports:
“ "At 3:31 p.m., a masseuse arrived at Apartment 5A of 421 Broome Street in SoHo for an appointment with Ledger, the police said. The masseuse was let in to the home by a housekeeper, who then knocked on the door of Ledger’s bedroom. When no one answered, the housekeeper and the masseuse opened the bedroom and found Ledger unresponsive. They shook him, but he did not respond. They immediately called the authorities. The police said they did not suspect foul play and said they found pills near his body[22][23]