By Rachel Parsons and Nichola Groom
LOS ANGELES, Dec 4 (Reuters) - Tesla Chief Executive Elon Musk was due to resume testifying in his own defense on Wednesday at the trial for a defamation lawsuit filed by a British diver whom the Silicon Valley billionaire called "pedo guy" on Twitter.
Musk, the 48-year-old South African-born entrepreneur, apologized for the tweet during his first day on the witness stand in U.S. District Court in Los Angeles on Tuesday, saying he was responding to an "unprovoked" insult by plaintiff Vernon Unsworth.
Unsworth was leading a rescue of 12 boys and their soccer coach from a flooded cave in Thailand last year when he mocked Musk's offer of a mini-submersible as a public relations stunt in an interview on CNN, adding that the Tesla Inc founder should "stick his submarine where it hurts."
"I assume he did not mean to sodomize me with a submarine. ... Just as I didn't literally mean he was a pedophile," Musk said from the witness stand under questioning by Unsworth's attorney, Lin Wood.
Unsworth is seeking unspecified compensatory and punitive damages from Musk, who also founded rocket company SpaceX, saying the false claims that he is a pedophile harmed his reputation.
Musk was called to testify on Tuesday by the plaintiff's lawyers after a jury was selected in the high-profile case and lawyers for both sides delivered opening statements.
U.S. District Judge Stephen Wilson has said the case hinges on whether a reasonable person would take Musk's tweet to mean that he was calling Unsworth a pedophile.
To win the defamation case, Unsworth needs to show that Musk was negligent in publishing a falsehood that clearly identified the plaintiff and caused him harm. "Actual malice" on Musk's part does not need to be proven because the judge has deemed Unsworth a private individual, not a public figure.
Although the case does not involve Tesla, Musk's Twitter habits have long been under close scrutiny, with the company's investors and regulators expressing concerns about his tweets.
With 29.8 million followers, Musk's social media account is a major source of publicity for his Palo Alto, California-based electric car company, which does not advertise.
In his opening statement, Unsworth attorney Taylor Wilson said the tweet was more than a slip-up, and Musk had wrongly branded Unsworth a predator "in what should have been one of the proudest moments of his life."
Musk lawyer Alex Spiro countered that Unsworth did not act after the tweet like a man who suffered because of it.
"The plaintiff is saying he has been horribly damaged, and deserves money," Spiro said. "He doesn't." (Additional reporting by Steve Gorman and Dan Whitcomb in Culver City, California; Writing by Dan Whitcomb; Editing by Peter Cooney)