Elon Musk has sent an additional letter of deal termination to Twitter Inc after the world's richest person subpoenaed a whistleblower seeking documents on how the social media company measures spam accounts.
Musk walked away from a $44-billion offer for Twitter in July saying the company misled him and regulators about the true number of spam or bot accounts on the microblogging platform.
According to a court filing on Monday, Musk has sought information from whistleblower and former head of Twitter's security Peiter Zatko mostly about the way the microblogging site measures spam account.
A famed hacker known as "Mudge," Zatko said in his complaint that became public last week that the company falsely claimed it had a solid security plan and prioritized user growth over reducing spam.
Following the disclosure, Musk's legal team said allegations on certain facts, which were known to Twitter prior to July 8 but were not disclosed to them, have come to light that provide additional and distinct bases to end the deal.
The subpoena to Zatko comes in the run-up to a five-day trial at the Delaware Court of Chancery set to begin on Oct. 17.
While Musk wants to terminate the deal, Twitter is asking Chancellor Kathaleen McCormick to order him to buy it for the agreed $54.20 per share.
Meanwhile, an additional termination notice dated Aug. 29 was delivered in case the July 8 notice was determined to be invalid for any reason, according to a regulatory filing by Musk on Tuesday.
Twitter shares were down 2.5% at $39.02 before the bell.