https://arstechnica.com/tech-policy/2019/10/report-musks-50000-pedo-guy-investigator-is-a-convicted-felon/

Last year, Vernon Unsworth, a cave explorer who advised on the rescue of kids trapped in a Thailand cave, got in a spat with Elon Musk. Musk labeled Unsworth a "pedo guy" in a tweet—and, in an ill-considered email to a reporter, later called him a "child rapist" who married a 12-year-old girl.

Unsworth sued Musk for defamation. Musk's legal response was that, while the accusations might not have been true, Musk believed they were true at the time he made them. The claim about marrying a 12-year-old (the woman in question says she was actually 33 when she met Unsworth) came from a private investigator to whom Musk paid $50,000 to dig into Unsworth's private life. Musk argued the high price tag was a sign that he was taking the issue seriously.