Andrew Tulloch, co-founder of the AI startup Thinking Machines Lab, is departing the company to join Meta. The AI researcher announced the move to employees in a message on Friday. A spokesperson for Thinking Machines Lab confirmed his departure, stating he “has decided to pursue a different path for personal reasons.”

This development follows an August report from The Wall Street Journal that Meta CEO Mark Zuckerberg had attempted to acquire Thinking Machines Lab. After the acquisition effort failed, Zuckerberg reportedly tried to recruit Tulloch with a compensation package potentially worth as much as $1.5 billion over at least six years. A Meta spokesperson at the time called the Journal’s description of the offer “inaccurate and ridiculous.”

Tulloch previously worked at OpenAI and Facebook’s AI Research Group. The startup he co-founded, Thinking Machines Lab, is led by former OpenAI CTO Mira Murati.