Steely Dan co-founder Walter Becker has passed away at the age of 67, an announcement on his website confirmed.

Becker joined up with Donald Fagen to form Steely Dan in the 70s and served as its two core members throughout the various lineup changes. After reforming Steely Dan in 1993, the pair experienced a burst of activity in the modern era, including their Rock and Roll Hall of Fame induction in 2001. Steely Dan was slated to head out on the road later this year.

Along with his work in Steely Dan, Becker also had an accomplished solo career, releasing two albums with the last coming in the form of 2008’s Circus Money.

No cause of death is currently known although Becker missed both of Steely Dan’s recent shows at the Classic West and East events. Fagen told Billboard that he was recovering from a procedure but did not elaborate on what type of surgery.