March 26 (Reuters) - A lawyer for Elon Musk urged a federal judge to review a recent jury verdict finding that Musk defrauded Twitter investors when buying the social media company, saying jurors improperly used the verdict to "send a message" by finding him liable.

In a letter filed on Thursday in San Francisco federal court, Musk's lawyer Alex Spiro accused jurors of "mocking" his client by writing the number "$4.20" in bright blue on the verdict form, though the remaining entries were written in black.

The number 420 is associated with marijuana culture. Musk, the world's richest person, has often mentioned 420 in interviews and tweets, and used it in business activities. He valued Twitter, now known as X, at $54.20 per share in his $44 billion buyout.

Spiro said the jury's "numerical joke" was "no doubt intentional," and when added to other alleged trial errors called into question the March 20 verdict, where damages could reach $2.5 billion. He said "further inquiry" by U.S. District Judge Charles Breyer, who oversees the case, was needed.

"The inescapable conclusion from the face of the verdict form is that the jury felt it appropriate to use its verdict to send a message to Mr. Musk, instead of properly discharging its solemn duty to render a just verdict," Spiro wrote.

Lawyers for the Twitter investors did not immediately respond to requests for comment.

MUSK ALSO USED '420' AT TESLA

Jurors found Musk liable for two statements he made not long after announcing the buyout, where he questioned whether Twitter was overrun by fake and spam accounts.

Investors said Musk did this to force Twitter to renegotiate his offer, or let him back out. They said Musk's comments hurt Twitter's stock price, causing losses when they sold their shares at depressed prices. Musk completed the acquisition in October 2022.

Musk has also used 420 in connection with his electric car company Tesla.

In 2020, for example, he cut the price of Tesla's Model S by 4% to $69,420. 

Two years earlier, he tweeted that he had "funding secured" to take Tesla private for $420 per share. The tweet prompted a U.S. Securities and Exchange Commission civil fraud lawsuit that Musk later settled.