David Roback, co-founder of the widely celebrated alt-rock group Mazzy Star, died Monday, a representative for the band confirmed. A cause of death was not revealed. Roback was 61.

Roback founded Mazzy Star with Hope Sandoval in the late Eighties and served as the band’s guitarist, keyboardist and producer. Between 1990 and 1996, Mazzy Star released three critically acclaimed albums that blended dream pop, psychedelia and touches of blues and folk with some of the blown-out textures of Nineties alt-rock: She Hangs Brightly in 1990, So Tonight That I Might See in 1993 and Among My Swan in 1996.

Mazzy Star seemed to go on hiatus in 1997 but returned in 2011 with a new single, then released their fourth album, Seasons of Your Day, in 2013. In an interview with Rolling Stone around the release of Seasons of Your Day, Sandoval and Roback said they’d never actually split, and had spent the years in between albums writing and recording, just not performing or releasing. Roback added that the point of all those sessions was simply to make music for themselves.

“When I’m working on music with Hope, the person that’s foremost in my thoughts is Hope,” Roback said. “We tend to get quite caught up in just the making of music for ourselves.”

In 2017, Mazzy Star’s long-time drummer, Keith Mitchell, died. The following year, the group released a new EP, Still.

Roback’s music career began in the Southern California psych revival scene of the early Eighties, known as the Paisley Underground. He played in several bands, such as Rain Parade and Rainy Day, and most notably partnered with Dream Syndicate’s Kendra Smith to form Opal. After Smith suddenly left Opal in the middle of a tour with the Jesus and Mary Chain, Roback tapped Sandoval to be her replacement, and the pair would eventually transform the group into Mazzy Star.