The bitter legal fight between Elon Musk and the leading artificial intelligence firm, OpenAI, led by Sam Altman, may come down to a few pages in one executive's personal diary.

Elon Musk’s courtroom showdown with Sam Altman got underway here Monday with the start of jury selection in a trial over the billionaire’s accusation that his OpenAI co-founders betrayed a non-profit ...

Legal discovery in the case has already unearthed titillating details involving a wide cast of characters, including Shivon Zilis, a former OpenAI board member and the mother of several of Musk’s chil...