Elon Musk has alleged that Twitter officials ordered a whistleblower to destroy evidence of their missteps as part of a $7.8-million severance package at issue in a legal fight over the billionaire’s attempt to cancel a buyout of the social media platform.

Peiter Zatko, Twitter’s ex-head of security, said he burned 10 handwritten notebooks and deleted 100 computer files at the behest of company managers as part of severance agreement, according to unsealed court filings. The books contained notes of the whistleblower’s meetings with company counterparts during his yearlong tenure as security chief, the filings show.

Zatko has been at the center of Musk’s arguments that Twitter misled him about a raft of operational problems at the social media platform — which justified walking away from the $44-billion buyout. The billionaire reversed course last week and agreed to buy the company for the original price of $54.20 a share.

“Twitter’s attempt to buy Mr. Zatko’s silence failed, but Twitter achieved its secondary aim of ensuring Mr. Zatko’s corroborating evidence would never come to light,” Musk’s lawyers said Monday in an unsealed filing in Twitter’s Delaware suit aimed at forcing the billionaire to consummate the deal.

Twitter didn’t immediately respond to Musk’s allegations in the filing.

Delaware Chancery Judge Kathaleen St. J. McCormick put the case on hold last week and set an Oct. 28 deadline for Musk and Twitter to complete the deal. Musk’s lawyers are asking McCormick to sanction Twitter’s attorneys for ordering the destruction of potential evidence in the case.

Zatko created a stir in Washington when he testified to the Senate Judiciary Committee last month that Twitter’s lax approach to computer security threatened U.S. security.

Twitter has said it fired Zatko in January for poor performance. The company said he gave “a false narrative about Twitter and our privacy and data security practices that is riddled with inconsistencies and inaccuracies and lacks important context.”

Zatko said he warned Twitter CEO Parag Agrawal about serious computer security issues and privacy concerns tied to the social media platform’s operations that amounted to violations of settlements the company reached with government regulators. He also said his Twitter colleagues showed little interest in doing a deep dive into the issue of how many spam and robot accounts were included among the company’s more than 230 million users.

Musk’s lawyers accuse Twitter’s top two lawyers, Vijaya Gadde and Sean Edgett, and Chief Privacy Officer Damien Kieran, along with Agrawal, of seeking to cover up the violations of the legal settlements by ordering Zatko to destroy his documents.

The document-destruction order deprived Musk’s legal team of “critical corroborating evidence of Mr. Zatko’s allegations, which would support his account of key meetings and conversations relevant to this case,” according to the unsealed filing.

Meanwhile, Twitter complained in its own unsealed filing that Musk’s top aide, Jared Birchall, showed up to his Sept. 21 pretrial deposition in the case unprepared to answer questions about a host of issues related to the transaction.

“Throughout the deposition, Birchall unequivocally conceded both his lack of knowledge and his lack of preparation — on topic after topic,” Twitter’s legal team said in the filing. Birchall runs Musk’s family office and was deeply involved in the negotiations over the buyout of the platform.

Twitter’s lawyers said Birchall had little or no information about his communications with government regulators about the deal, the hiring of data scientists to review the number of spam or robot accounts embedded in Twitter’s customer base, or the Musk side’s efforts to retrieve relevant messages about the transaction.

A spokesman for Musk’s lawyers didn’t immediately respond Monday to a request for comment about Twitter’s complaints about Birchall’s deposition performance.