Howie Epstein, former bassist for Tom Petty and the Heartbreakers, died Sunday at a hospital in Santa Fe, New Mexico, at the age of 47.

The cause of death has not been determined, but officials suspect the musician was killed by a heroin overdose. According to Maj. Ron Madrid of the Santa Fe Sheriff's Department, a female friend of Epstein's brought him into St. Vincent's Hospital after he passed out in her bathroom. Epstein was still breathing when he entered the hospital but never regained consciousness.

The friend gave investigators antibiotics that Epstein had been taking for the flu and "physical evidence that he had been doing heroin," Madrid said. He would not specify what that evidence was.

An autopsy was performed Monday, but toxicology reports have not come back. Authorities hope to establish the cause of Epstein's death by the end of the week.

In June 2001, Epstein and then-girlfriend Carlene Carter (stepdaughter of Johnny Cash and daughter of June Carter Cash) were found in a car that had been reported stolen and were arrested for possessing 2.9 grams of black tar heroin and drug paraphernalia. Carter pleaded no contest to a charge of heroin possession and was sentenced to 18 months of probation. In May 2002, Petty and the Heartbreakers replaced Epstein with their original bassist, Ron Blair, reportedly due to his personal problems.

"We are deeply saddened at the news of Howie's passing," Tom Petty and the Heartbreakers said in a statement. "It's difficult to put into words how much we loved him and will miss him. The world has lost a great talent and a kind and gentle soul. We can only take solace in knowing he is now at peace. Our thoughts and prayers are with his family and his many friends."

Epstein's career as a musician and producer spanned more than two decades. In addition to playing bass as a member of the Heartbreakers, he contributed to some of Bob Dylan's albums and produced John Prine's Grammy-winning 1991 folk album, The Missing Years.

Epstein is survived by daughter Jamie Leffler, 15, in Los Angeles and two brothers in Milwaukee.