The Who's bass guitarist John Entwistle died from a heart attack caused by cocaine use, according to a coroner in Las Vegas.
Clark County Coroner Ron Flud ruled the rock star's death to be accidental but said it was not an overdose.
Entwistle's body was found June 27 in his bed at a room in the Hard Rock Hotel. He was 57.
"The heart attack we believe was brought on by the significant amount of cocaine that was in Entwistle's system at the time, although the specific amount remains unknown," Mr Flud said.
"Cocaine is a different animal. It's not like alcohol. There's no way we can put a number on it. You've got a lethal drug on board at the time you have a bad heart; that's a bad combination."
Entwistle's death was caused when cocaine caused the contraction of the coronary arteries that were already damaged by heart disease, Mr Flud confirmed.
The co-founder of The Who was on medication for a heart condition, according to Steve Luongo, the drummer in another Entwistle band for the past 15 years.
Entwistle died the day before The Who was scheduled to kick off a three-month US tour at the hotel's concert hall.
Clark County District Attorney Stewart Bell said no criminal charges were anticipated.
"From a legal point of view, there isn't anything to be done, because we don't have anybody else who might be responsible," he said.