Leaders at Mira Murati’s Thinking Machines Lab confronted the startup’s cofounder and former CTO, Barret Zoph, over an alleged relationship with another employee last summer, WIRED has learned.

That relationship was likely the alleged “misconduct” that has been mentioned in prior reporting, including by WIRED.

To protect the privacy of the individuals involved, WIRED is not naming the employee in question. The individual, who worked in a different department than Zoph and was in a leadership role, is no longer at the lab.

Murati approached Zoph to discuss the relationship, sources say. The cofounders’ working relationship broke down in the months following that conversation, according to multiple sources, and Zoph started speaking to competitors about other opportunities.

Before Zoph left the company, he was in conversation with leaders from Meta Superintelligence Labs, according to a source familiar with the matter. Zoph was ultimately hired by OpenAI. OpenAI’s CEO of applications, Fidji Simo, said the hiring had been in the works for weeks. Simo also noted that she did not share Thinking Machines’ concerns over Zoph’s ethics.

Zoph and OpenAI declined to comment for this story.

This week, a third Thinking Machines cofounder, Luke Metz, and at least three other researchers from Murati’s startup also departed for OpenAI. In October, the startup’s cofounder Andrew Tulloch left for Meta.

While tensions between Murati and Zoph came to a head in recent days, they do not entirely explain the broader exodus of Thinking Machines employees.

WIRED previously reported that there was misalignment within Thinking Machines about what the startup should build.

In November, Murati’s startup was reportedly looking to raise capital at a $50 billion valuation, up from its current valuation of $12 billion.

Thinking Machines Lab declined to comment for this story.