In July, Musk called Unsworth a pedophile in a tweet and said he would bet money to back his accusation after Unsworth, who was involved in the Thailand cave rescue, said the miniature submarine Musk designed and sent to Thailand to help with the rescue would have been ineffective and was merely a publicity stunt.
On Tuesday, the Tesla CEO tweeted in reply to former TechCrunch writer Drew Olanoff that it was "strange" that the diver, Vernon Unsworth, had not sued him, considering he was "offered free legal services".
Musk told Olanoff that he found it odd that Unsworth has not sued him, adding that Unsworth was even offered "free legal services".
The Tesla CEO and co-founder resurrected his calling of Vern Unsworth, the British diver who assisted in the Thai cave rescue last month, a "pedo" while conversing on Twitter on Tuesday.
The letter, dated August 6, said the possible lawsuit would cover "false and defamatory statements" made by Musk against Unsworth.
"I think sometimes people think I spend a lot of time in Twitter", he told the YouTuber Marques Brownlee earlier this month.
He ended the exchange by suggesting that Olanoff was not a "truth-seeker" because he didn't investigate why Unsworth hadn't sued Musk. L. Lin Wood, a defamation lawyer based out of Georgia, tweeted a letter earlier Wednesday dated to August 6, 2018.
In an interview with CNN, Unsworth said: "He [Musk] had no conception of what the cave passage was like". "You did so without any basis".
Mr Musk's latest tweet was written in response to a former journalist, who had accused him of hypocrisy.
While the rest of the world was celebrating the successful rescue, Mr Musk's offensive comments have cast a shadow over Mr Unsworth. "According to a subsequent Twitter post, you did so out of anger". Musk's Twitter page has been prone to these tweets, as the platform lacks moderation or voting mechanisms, allowing for scammers to reach the top of the reply chain easily.
"He's not going to become a typical CEO, so the question is whether he's going to make statements that run afoul of securities laws", said Ken Bertsch, an executive director at the Council of Institutional Investors, a trade group that represents public pension funds that own Tesla shares.