CHICAGO (CBS) — An autopsy Sunday came back inconclusive, but officials say it does appear that Weezer’s former bass player Mikey Welsh died of a drug overdose.

As WBBM Newsradio’s Michele Fiore reports, Welsh was in Chicago to watch his former band play at the Riot Fest, a multi-venue punk music festival. But instead, Welsh wound up dead at the Rafaello Hotel, 201 E. Delaware Pl.

LISTEN: WBBM Newsradio’s Michele Fiore reports

Police News Affairs Officer Laura Kubiak said Welsh was supposed to check out of the hotel at 1 p.m. Saturday. When he didn’t, hotel staff went to his room, entered it and found him unconscious and not breathing, Kubiak said.

The cause of death was undetermined pending toxicology tests, according to an autopsy performed Sunday by the Cook County Medical Examiner’s Office. Test results could take up to six weeks, authorities said.

Welsh, 40, of Burlington, Vt., played with Weezer from 1998 to 2001, when he suffered a nervous breakdown and left the band. He later began a second career as a painter, gaining worldwide acclaim for large-scale figures and abstracts.

He became a pinnacle artist on the Outsider Art scene with his mixed media and mural works and live panting projects. Quoted on his Web site, the Boston Globe said he turned “oils, acrylics, house paint, brush-stroked words, and pages torn from newspapers or porn mags into images that seduce the eye and ignite the mind.”

But to fans, Welsh always remained associated with Weezer, having appeared on many of their most popular hits.

“People know him from the Green Album, because everybody knows ‘Hash Pipe’ and ‘Island in the Sun’ and ‘Crab,’” said fan Victoria Holda. The Green Album was released in 2001.

Welsh checked himself into a psychiatric hospital in August 2001, and was replaced by bassist Scott Shriner afterward, according to published reports.

“I’m taking a break from music,” Welsh told MetroWest Daily News in 2002. “I really feel the need to reinvent myself and move on, and I couldn’t be happier painting. Music is still an important part of my life, but I really have no desire to actually play it.”

Weezer posted a message on its website, saying Welsh’s time with the band was “vital, essential, wild, and amazing.”

“A unique talent, a deeply loving friend and father, and a great artist is gone, but we will never forget him,” the band said.

But the band honored its commitment to headline the Riot Fest Sunday at the Congress Theater, 2135 N. Milwaukee Ave.

“While everyone is still in shock over yesterday’s tragic loss of Mikey Welsh, we know damn well he would never have wanted to stop the rock at today’s Riot Fest, the show he was planning on attending,” Weezer said on the band Web site Sunday. “On the contrary, the rock was what he loved, both in music and art. To play the show and play it well tonight is to honor him and his memory. We have a feeling he will be watching.”

Some fans who came to see Weezer at the Congress Theater were crying as the band took the stage.

“A lot of people are going to be sad,” said fan Juan Pintor.

Weezer was founded in Los Angeles in 1992 by lead singer Rivers Cuomo.

(TM and © Copyright 2011 CBS Radio Inc. and its relevant subsidiaries. CBS Radio and EYE Logo TM and Copyright 2011 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed. The Associated Press contributed to this report.)

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