Elon Musk has submitted more paperwork to the court in the legal fight with Twitter. This time, Musk cited a recent whistleblower’s claims as further reason the acquisition is invalid. Last week, the former head of security at Twitter, agreed to be identified as Peiter “Mudge” Zatko, said the social media platform has “extreme and egregious deficiencies” related to cybersecurity issues that put the company’s users, shareholders and national security at risk.

Musk argued in Monday’s filing the claims are further evidence Twitter violated its contract agreement. The court filing reads “these facts were known to Twitter and withheld from the Musk Parties, and because Twitter has since taken the position that the Merger Agreement remains in effect, the Musk Parties hereby provide this additional notice of termination of the Merger Agreement.”

“This doesn’t have to do with Elon Musk,” John Tye, an aide to the Twitter whistleblower, said. “He contacted us in early March. He’s been working on lawful disclosures since even December of last year, 2021. So this, his concerns arose well before Elon Musk or anyone else ever talked about buying Twitter.”

Musk has subpoenaed the whistleblower and former Twitter CEO Jack Dorsey ahead of trial. Twitter has already responded. It said the new filing is based on flawed, inaccurate statements coming from a third party and that the deal is still valid.

“Contrary to the assertions in your letter, Twitter has breached none of its representations or obligations under the Agreement, and Twitter has not suffered and is not likely to suffer a Company Material Adverse Effect,” Twitter continued. “Twitter intends to enforce the Agreement and close the transaction on the price and terms agreed upon with the Musk Parties.”

Both Musk and Twitter are busy preparing their cases for an Oct. 17 court appearance.