STORY: Zatko said on Tuesday that in the week before he was fired from Twitter, he learned an agent of China's Ministry of State Security, or MSS, an agency comparable to the U.S. Central Intelligence Agency, was on the payroll at Twitter.
It was not immediately clear if the alleged Chinese agent was still working at the company.
Twitter did not immediately respond to a request for comment on Zatko's testimony.
In his testimony, Zatko said he recalled a conversation with another Twitter executive about concerns that a foreign agent was inside the company. The executive responded "Well, since we already have one, what does it matter if we have more?"