Missouri Republican Gov. Eric Greitens was indicted Thursday by a St. Louis grand jury on a felony invasion of privacy charge, according to a news release from Circuit Attorney Kimberly Gardner.

The charge stems from an incident that allegedly occurred in March 2015, she said.

Greitens, 43, was booked at the St. Louis Justice Center, officials confirmed to the St. Louis Post-Dispatch. He was released on his own recognizance, St. Louis Circuit Attorney spokeswoman Susan Ryan told The Associated Press.

According to Gardner’s news release, the grand jury “found probable cause” that Greitens broke a state law.

The indictment said Greitens allegedly took a photo of a person – who was only identified by their initials – “in a state of full or partial nudity” without their knowledge or consent and “in a place where a person would have a reasonable expectation of privacy,” according to the Post-Dispatch.

It goes on to say that Greitens allegedly “transmitted the image contained in the photograph in a manner that allowed access to that image via a computer,” which is a felony, according to Gardner’s release.

Missouri Gov. Eric Greitens outlines his tax overhaul plan to supporters at Doyle Manufacturing Monday, Jan. 29, 2018, in Palmyra, Mo. Greitens is calling for cuts in personal income tax and reductions in corporate taxes as part of what he has described as the "boldest state tax reform in America." (AP Photo/Jeff Roberson)

Greitens previously admitted to having an affair.  (AP)

An investigation into Greitens’ behavior was opened in January following his admiting to an affair, reportedly beginning in March 2015.

Local reports at the time said Greitens allegedly threatened to publicize nude images of the woman he was having the extramarital relations with if she exposed their relationship, according to her ex-husband.

The man secretly recorded a conversation with his then-wife, in which she reportedly admitted to having an affair with Greitens.

While acknowledging that he was “unfaithful” in his marriage, Greitens denied allegations that he blackmailed the woman.

Gardner declined to comment to The AP but Ryan confirmed the indictment stemmed from the alleged photo.

Greitens’ lawyers called the charges “baseless and unfounded,” in a statement to the Post-Dispatch. He’ll reportedly file a motion to dismiss the charges.

The Missouri governor was elected in November 2016.

Greitens is a decorated former Navy SEAL officer whose received a Bronze Star and Purple Heart, among other awards, according to his service record. He enlisted in the Navy in 2000.

Fox News’ Lucas Tomlinson and The Associated Press contributed to this report.