(Adds potential damages, closing argument from plaintiff's lawyer)
By Nichola Groom and Rachel Parsons
LOS ANGELES, Dec 6 (Reuters) - Tesla founder Elon Musk should pay at least $190 million in damages for defaming a British cave explorer in tweets that suggested he was a pedophile and were like a "nuclear bomb," the plaintiff's lawyer said on Friday.
In his closing argument at Musk's defamation trial, the lawyer for Vernon Unsworth said his client would feel the sting from Musk's calling him a "pedo guy" for many years to come, affecting his relationships and job prospects, and jurors should teach the "billionaire bully" a lesson.
At least $150 million of the proposed payout would be punitive damages, which Unsworth's lawyer L. Lin Wood said "would be a hard slap on the wrist" for Musk, who during the trial estimated his own net worth at $20 billion.
"He dropped a nuclear bomb on Vernon Unsworth," Wood said, referring to Musk.
A lawyer for Musk will also deliver a closing argument on Friday and the three-man, five-woman jury may begin deliberating later in the day. The trial in federal court in Los Angeles began on Tuesday.
The case is believed to be the first major defamation lawsuit by a private individual to go to trial over tweets.
Musk could appeal if the jury finds him liable or imposes a large damages award.
Unsworth gained fame when he helped coordinate the rescue of a boys' soccer team and its coach from a flooded Thailand cave, which was completed successfully on July 10, 2018.
Three days later, Unsworth gave an interview on CNN where he criticized Musk's offer of a mini-submarine to help with the rescue as a "PR stunt" and that Musk could "stick his submarine where it hurts."
Two days later, on July 15, 2018, Musk fired off the three tweets underlying the lawsuit, questioning Unsworth's role in the rescue and calling him "pedo guy," with no evidence.
In his own testimony, the 48-year-old Musk called the tweets an "off the cuff" response to viewing a replay of the interview.
He said it was perhaps borne of fatigue from spending 80 to 100 hours a week running Tesla, which makes electric cars, and SpaceX, the rocket company where the mini-submarine would have come from.
Unsworth, 64, testified on Thursday that his own insult was "not to Mr. Musk personally" and declined to apologize.
"I'm not sure how I need to apologize. It was my opinion at the time and I stand by that opinion," Unsworth said when cross-examined by one of Musk's lawyers.
The trial has revived discussion of Musk's erratic behavior during 2018.
This included when he used Twitter to float a leveraged buyout proposal for Tesla that was nowhere near a reality, prompting a U.S. Securities and Exchange Commission lawsuit that he paid $20 million to settle.
For most of 2019, Musk, who has more than 29.9 million Twitter followers, has largely kept his public comments focused on Tesla's new models and improved profitability and on the technical progress of his SpaceX aerospace company.
To win the case, Unsworth must prove Musk was negligent in publishing a falsehood that clearly identified him and caused him harm.
He does not need to show Musk acted with "actual malice," which is much tougher to prove.
If jurors found Musk liable, their assessment of what he had been thinking would likely affect the amount of punitive damages they assess. (Additional reporting by Steve Gorman and Dan Whitcomb in Los Angeles, and Jonathan Stempel in New York; Editing by Edwina Gibbs and Grant McCool)
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