Peiter Zatko, the Twitter whistleblower will be testifying in front of the Senate Judiciary Committee on September 13, the leaders of the panel announced on Wednesday.

This is the second subpoena that the former Twitter security chief has received ever since the contents of Zatko’s complaint to regulators were made public. The first one was from Elon Musk’s lawyers who have been looking for more information on Twitter after the tech billionaire pulled out of the $44 billion deal to buy the company.

On 24 August Zatko went public with his allegations of lax cybersecurity at the microblogging site’s offices, saying that their servers were out of date, copies of Twitter’s source code were floating around employee systems and a host of other complaints. 

In a statement, the chair of the committee, Senator Dick Durbin of Illinois, along with Chuck Grassley of Iowa said that Zatko’s allegations of foreign nation interference and gaps in security had raised “serious concerns”.

The former DARPA project manager had joined the company in 2020, just months after the accounts of high-profile Twitter users were hacked. He spent two years at the company and was fired in January 2022, shortly after the exit of Twitter’s co-founder Jack Dorsey in November 2021. 

One of the more explosive claims made by Zatko is that Twitter’s head of site integrity had informed him that the company had no way of knowing how many spam and bot accounts it had on its platform. 

Since Zatko’s complaints went public, Twitter has moved to release its own version of the events, saying that the 51-year-old’s statement was “riddled with inconsistencies and inaccuracies” and that he had been fired because of “ineffective leadership and poor performance.”

The complaint has likely bolstered the tech billionaire’s case against buying Twitter. Musk had pulled out the deal saying the Twitter had misled him about the spam accounts on the platform and that the departure of high profile executives had also contributed.