Autopsy results for the rapper known as O.D.B., who died at a Manhattan recording studio, will not be available for several days while authorities conduct medical tests, the New York City medical examiner's office said yesterday.

O.D.B. complained of chest pains before collapsing Saturday. He was dead by the time paramedics reached him, said Gabe Tesoriero, a spokesman for Roc-A-Fella Records. The cause of death was not clear, but O.D.B. had recently finished a prison sentence for drug possession and escaping a rehab clinic. He would have turned 36 today.

The music world mourned the rapper's death as stars gathered in Los Angeles for the 32nd annual American Music Awards. O.D.B., also known as Ol' Dirty Bastard, was a founding member of the rap group Wu-Tang Clan. With his unorthodox delivery -- alternately slurred, hyper and nonsensical -- O.D.B. stood out even in the nine-man Clan, and as a solo artist he released hit singles such as "Shimmy Shimmy Ya" and "Got Your Money."

The rapper was born Russell Tyrone Jones in Brooklyn, and grew up on welfare in the Fort Greene neighborhood. He and his cousins Robert Diggs and Gary Grice parlayed their taste for rap music and kung fu movies into the Staten Island-based Wu-Tang Clan, renaming themselves, respectively, Ol' Dirty Bastard (since there was no father to his style), the RZA and the Genius. Their first album, "Enter the Wu-Tang (36 Chambers)," was released at the end of 1993 and became one of the most influential rap albums of the decade.

O.D.B. had been working on his comeback album for more than a year and was almost finished, Tesoriero said.

Information about funeral plans was not available.

Staff writer Joe Holley contributed to this report.