Records made public on Monday show Dorsey was served with a legal order to give Musk any communications or documents related to the takeover deal inked in April, as well as information touching on false or spam accounts or how Twitter calculates the number of its active users.

In this file photo taken on September 3, 2020 Tesla CEO Elon Musk talks to media as he arrives to visit the construction site of the future US electric car giant Tesla, in Gruenheide near Berlin. Elon Musk has served August 22, 2022 former Twitter boss Jack Dorsey with a subpoena in a hunt for material to help him get out of buying the giant social media platform for $44 billion as agreed. Odd ANDERSEN / AFP

The subpoena asks for anything Dorsey has on the topics dating back to January of 2019.

Tesla boss Musk, the world's wealthiest man, has accused Twitter of fraud, alleging the company misled him about key aspects of its business, particularly the number of accounts that are actually spam or automated "bots" instead of people.

Twitter has stuck by its estimates that bots make up fewer than five percent of users.

Twitter also disputed Musk's assertion he has the right to walk away if its bot count is found to be wrong, since he didn't seek information on that topic when he made the buyout offer.

The company accuses Musk of contriving a story to escape a merger agreement that he no longer found attractive.

"Musk's counterclaims, based as they are on distortion, misrepresentation, and outright deception, change nothing," Twitter said in a court filing.

Rival lawyers have been serving subpoenas for weeks seeking documents or depositions from a wide range of people connected with the buyout, running Twitter's business, and even with a holding company formed by Musk.

Twitter co-founder Dorsey in November of last year ended his second stint as chief of the company and had voiced support for Musk taking it over.

The Twitter deal included a provision that if the deal fell apart, the party breaking the agreement would pay a termination fee of $1 billion under certain circumstances.

Billions of dollars are at stake, but so is the future of Twitter, which Musk has said should allow any legal speech -- an absolutist position that has sparked fears the network could be used to incite violence.

The legal fight is gathering speed as preparations have begun for an October trial in Delaware's Chancery Court, which specializes in complex, high-stakes business battles.

Twitter has urged shareholders to endorse the deal, setting a vote on the merger for September 13.

While fielding questions at a recent Tesla shareholders meeting, Musk was asked whether his potential ownership of Twitter might distract from his running of the electric car company.

"I think Tesla, you know, would continue to do very well even if I was kidnapped by aliens, or went back to my home planet," he joked, drawing laughter and applause.

"To be frank, I don't have an easy answer," Musk added.

He assured shareholders that, for now, he has no plans to leave his Tesla chief role.