Former Y Combinator partner and chief operating officer Qasar Younis has left the company to work “on something new,” according to the departing executive’s personal site and Facebook account.

Younis first participated in the accelerator in 2010 as an entrepreneur. Three years later, he joined Y Combinator as an investor after selling his company, TalkBin, to Google.

Y Combinator president Sam Altman made Younis the accelerator’s first COO in August 2015 and tasked him with scaling the “organization and operations as we tackle bigger and more ambitious projects,” Altman wrote at the time. Younis was at one point in charge of managing both Y Combinator’s daily affairs and its slate of events, including demo days and the Female Founders conference.

We’ve reached out to Y Combinator for more details on Younis’ departure. We’ll update this story when we hear back.