Body of actor Heath Ledger is removed from Soho apartment by NYC Medical Examiner team, 22 Jan 2008

New York City medical examiners say initial autopsy results of actor Heath Ledger are inconclusive and that more tests are needed to determine the cause of his death.

The Academy-Award-nominated actor was found unconscious Tuesday in a Manhattan residence with bottles of sleeping pills nearby. He was 28-years-old.

President Bush postponed an event Wednesday, promoting an advertising campaign on preventing prescription drug abuse. White House spokeswoman Dana Perino says the administration does not want anyone to think it is tying the actor's death to the issue.

Heath Ledger, left and Jake Gyllenhaal in scene from Brokeback Mountain

The Australian-born Ledger was nominated for an Academy Award for his role in the 2005 movie Brokeback Mountain.

He will appear later this year in the newest Batman movie, The Dark Knight, in the role of "the Joker."

Ledger has a two-year-old daughter, Matilda, from his relationship with actress Michelle Williams, who played his wife in Brokeback Mountain. The couple broke up last September.