Kelley's body was discovered in the bathtub of his South Pasadena property by a friend on Tuesday night (31Jan12), according to Los Angeles County Coroner's spokesman Ed Winter.
Reuters reports authorities are investigating the possibility that Kelley took his own life. An autopsy is scheduled for Thursday (02Feb12).
Paul Schimmel, chief curator for the Los Angeles County Museum of Contemporary Art, says, "It's a terrible loss for his family and friends and for the artists of this community, which he's done so much to change and enrich.
"I saw Mike just before the holidays and had just a wonderful evening with him. He was thinking about important opportunities for change in his life going forward, so this all comes as a terrible, tragic shock."