According to charges unsealed on Wednesday by the justice department on Wednesday she defected to Iran in August 2013, taking with her details of U.S. counter-intelligence agents she had worked with, who were then targeted by Iranian hackers, four of whom are named in the indictment and charged alongside Witt.
According to an undated Federal Bureau of Investigation missing persons declaration regarding Witt, she had not been in contact with anyone since 2013.
"She made a decision to turn against the United States and shift her loyalty to Iran", said Jay Tabb, the FBI's executive assistant director for national security.
Provided with housing and computer equipment by the Iranian government, Witt tracked down USA counterintelligence agents she used to work with on Facebook, the indictment said, and disclosed the classified identity of at least one of those agents, according to the charges.
"It is a sad day for America when one of its citizens betrays our country", said Assistant Attorney General John Demers, announcing the indictment.
Witt, who served in the US Air Force from August 1997 to March 2008 and worked from 2008 to 2010 as a government contractor on classified projects, had access to sensitive government materials, officials said.
The announcement, which also included sanctions on the New Horizon Organization, organization officials, and a company tied to the hacking effort, came on the opening day of a US-led global conference in Warsaw, Poland aimed at boosting pressure on Tehran.
In 2013, Witt traveled to Iran for that year's "Holywoodism" conference.
In 2012, after Witt travelled to Iran for a conference, the FBI warned her that she could be a targeted for recruitment by that country's government, and Witt told the bureau she would refuse to provide information about her military work, according to the indictment. "Thanks for giving me the opportunity". Iran's nuclear program was the target of the U.S.
The Department of Treasury accuses Net Peygard Samavat Company of being "involved in a malicious cyber campaign to gain access to and implant malware on the computer systems of current and former counterintelligence agents".
While in Iran, she also allegedly converted to Islam during a television segment after identifying herself as a United States veteran, and delivered several broadcasts in which she criticised the US.
The Justice Department has issued arrest warrants for Witt and the four Iranians, who all remain at large.
What's the state of US-Iran relations?
Last November, US President Donald Trump re-imposed all sanctions on Iran that had been suspended due to the 2015 Joint Comprehensive Plan of Action (JCPOA) nuclear agreement.
The US and Iran do not maintain diplomatic relations, and communications between the two nations are exchanged through Swiss diplomats.