A diver who helped rescue boys trapped in a Thailand cave may sue Elon Musk after the tech billionaire called the rescuer a "pedo guy."

Diver Vernon Unsworth was instrumental in the rescue, and he said that Musk's attempt to build a small submarine for the rescue effort was a "PR stunt" that had no chance of working. Musk soon promised to prove Unsworth wrong—and lobbed a baseless charge of pedophilia at the rescuer.

In a series of tweets yesterday, Musk initially challenged Unsworth to "show [the] final rescue video" before writing, "You know what, don't bother showing the video. We will make one of the mini-sub/pod going all the way to Cave 5 no problemo. Sorry pedo guy, you really did ask for it."

Musk, the CEO of SpaceX and Tesla, offered no evidence or justification for his claim that Unsworth is a pedophile. When another person on Twitter pointed out that Musk is "calling the guy who found the children a pedo," Musk responded, "Bet ya a signed dollar it's true." Musk has since deleted the tweets.

Musk's outburst came just a week after he said in a Bloomberg interview that he would try to be less combative on Twitter. "I should probably say nothing more often," Musk said at the time.

Unsworth, 63, is British and lives in Thailand for part of the year. He could sue Musk for libel in a British court. As The Guardian reported:

Unsworth told journalists at the cave site, where a cleanup operation is under way, that the remarks about him were an attack on the entire rescue crew. "I believe he's called me a pedophile," he said. "I think people realize what sort of guy [Musk] is." Asked if he would consider taking legal action against Musk, he told reporters: "Yes, it's not finished."

A lawyer who spoke to The Guardian called it "a cast-iron case of libel."

Thai Cave Rescue: British diver Vern Unsworth has told 7 News' @MyleeHogan that he's considering legal action after being referred to as 'pedo guy' by @elonmusk. "It's not finished...I believe he's called me a 'paedophile'...I think people realise what sort of guy he is." #7News pic.twitter.com/jzVUAtraun — 7 News Sydney (@7NewsSydney) July 16, 2018

Unsworth said he would sue Musk if the pedophile accusation is "what I think it is," according to AFP. At the time, Unsworth hadn't yet read Musk's tweets but had been told about them.

"The caver told AFP he would make a decision when he flies back to the UK this week, but said the episode with Musk 'ain't finished,'" the news agency reported.

"He's just a PR stunt merchant—that's all he is," Unsworth added.

Divers completed the rescue of 12 boys last week while saying that Musk's submarine was "not practical for this mission." Unsworth's knowledge of the cave system's layout reportedly was crucial in the rescue.

Musk made his "pedo guy" comment in a tweet to Zeynep Tufekci, a University of North Carolina professor who recently wrote a New York Times op-ed titled, "What Elon Musk Should Learn From the Thailand Cave Rescue."

Tufekci was surprised by Musk's tweet. "I’m dumbfounded by this," Tufekci wrote on Twitter. "I’d understand getting mad at me... but Vern Unsworth is, by all accounts I saw, a key hero of the miraculous rescue. The kids certainly—and many more divers likely—would be dead if not for him."