Musk was an early investor in OpenAI when it was founded in 2015 and cochaired its board alongside Altman. In the lawsuit, he said he invested “tens of millions” of dollars and recruited top AI research scientists for OpenAI. Musk resigned from the board in early 2018 in a move that OpenAI said—at the time—would prevent conflicts of interest as he was recruiting AI talent to build self-driving technology at Tesla.

The electric car maker CEO dropped his previous lawsuit against OpenAI without explanation in June. That lawsuit alleged that when Musk bankrolled OpenAI’s creation, he secured an agreement with Altman and Brockman to keep the AI company as a nonprofit that would develop technology for the benefit of the public and keep its code open.

“As we said about Elon’s initial legal filing, which was subsequently withdrawn, Elon’s prior emails continue to speak for themselves,” a spokesperson for OpenAI said in an emailed statement. In March, OpenAI released emails from Musk showing his earlier support for making it a for-profit company.

Musk claims in the new suit that he and OpenAI’s namesake objective were “betrayed by Altman and his accomplices.”

“The perfidy and deceit are of Shakespearean proportions,” the complaint said.

—Sarah Parvini, Associated Press technology writer