ST. LOUIS (AP) — Missouri Gov. Eric Greitens remains defiant, even amid calls for impeachment or resignation, after a St. Louis grand jury indicted him for felony invasion of privacy, alleging the Republican took a compromising photo of a woman during an extramarital affair the year before he was elected.

St. Louis Circuit Attorney Kim Gardner on Thursday announced the indictment that followed an investigation launched in January, a day after Greitens admitted to an affair with his St. Louis hairdresser that began in March 2015.

Greitens released a statement saying he made a mistake but “did not commit a crime.” He accused Gardner, a Democrat who was also elected in November 2016, of playing politics.

“With today’s disappointing and misguided political decision, my confidence in our prosecutorial system is shaken, but not broken,” Greitens said. “I know this will be righted soon. The people of Missouri deserve better than a reckless liberal prosecutor who uses her office to score political points.”

Gardner’s spokeswoman, Susan Ryan, responded: “Despite the Governor’s personal attacks, the Circuit Attorney believes the courtroom is the appropriate place to argue the facts, not the media.”

Greitens canceled plans to go to Washington this weekend the National Governors Association annual meeting. In a statement Friday, the Republican Governors Association said Greitens informed the group he would stay in Missouri “to fight back against what his team has called a baseless charge.” The group said Greitens also “no longer intends to serve” on its executive committee.

Greitens’ attorney called the indictment “baseless and unfounded.” Attorney Edward L. Dowd Jr. filed a motion to dismiss the indictment on the grounds that any relationship with the woman was consensual.

A few lawmakers from both parties suggested that Greitens should consider resigning, just as they did after he admitted to the affair on Jan. 10.

House Republican leaders announced they were forming a group of lawmakers to investigate the charges “and answer the question as to whether or not the governor can lead our state while a felony case moves forward.” Dowd said the governor welcomes the review.

The joint statement from House Speaker Todd Richardson, Speaker Pro Tem Elijah Haahr and Majority Leader Rob Vescovo did not specifically mention impeachment, a process that must begin in the House with an investigation.

But for some lawmakers, impeachment is on the table.

“Gov. Greitens has to go,” Democratic state Sen. Jamilah Nasheed of St. Louis said. “Missourians thought they voted for a person of character and integrity, and instead they got a liar and alleged criminal.”

Greitens, 43, has frequently vowed that he won’t step down. He indicated Thursday he intends to stay and fight.

“This will not for a moment deter me from doing the important work of the great people of Missouri,” Greitens said in the statement.

The indictment states that on March 21, 2015, Greitens photographed a woman identified only by her initials “in a state of full or partial nudity” without her knowledge or consent. The indictment said Greitens “transmitted the image contained in the photograph in a manner that allowed access to that image via a computer.”

Soon after the affair began, the woman’s husband secretly recorded a conversation in which she described the alleged incident. She said Greitens had bound her hands and blindfolded her in his St. Louis home, taken a photo of her partially nude, and then warned her to remain silent.

“I saw a flash through the blindfold and he said, ‘You’re never going to mention my name,'” she said.

Greitens has repeatedly denied blackmailing the woman, but has repeatedly refused to answer questions about whether he took a photo.

Greitens was taken into custody in St. Louis and released on his own recognizance. He is due in court for his first hearing on March 16, before Circuit Judge Rex Burlison. He could face up to a four-year sentence if convicted.

The statute of limitations for invasion of privacy in Missouri is three years, which means it was due to expire in less than a month.

Ryan, asked if additional charges could be filed, said the matter is still under investigation. Several lawmakers were questioned last week by investigators from Gardner’s office.

Greitens, the father of two young boys, came into office as a political outsider, a brash Rhodes Scholar and Navy SEAL officer who was wounded in Iraq, emerging as the winner in a crowded and expensive GOP primary.

A former boxer and martial arts expert, he has embraced the role of maverick. He responded to a Democratic attack ad in the fall of 2016 with one of his own in which he fired more than 100 rounds from a machine gun as an announcer declared he’d bring out “the big guns” to fight Democratic policies championed by then-President Barack Obama.

Greitens surprised many experts by defeating Democratic Attorney General Chris Koster in the November 2016 election. Some saw him as a rising Republican star with potential presidential aspirations.

But governing hasn’t always been easy, even though Republicans now control both houses as well as the governor’s mansion. Greitens and GOP lawmakers have often clashed, with him comparing some to third-graders and labeling them “career politicians.”

He has also faced questions about so-called “dark money” campaign contributions and criticism for stacking the state board of education. His use of a secretive app that deletes messages is under investigation by Republican Attorney General Josh Hawley.

Greitens’ charity, The Mission Continues, faced scrutiny during the campaign when Democrats accused him of insider politics for accessing the donor list to raise about $2 million through its top contributors.

A booking photo provided by the St. Louis Metropolitan Police Department shows Missouri Gov. Eric Greitens on Thursday, Feb. 22, 2018. A St. Louis grand jury has indicted Greitens on a felony invasion of privacy charge for allegedly taking a compromising photo of a woman with whom he had an affair in 2015, the city circuit attorney’s office said Thursday. Greitens’ attorney issued a scathing statement challenging the indictment. (St. Louis Metropolitan Police Department/St. Louis Post-Dispatch via AP)