It's unclear what, if any, evidence exists to back up claims that the young GOP governor sought to blackmail his former hairdresser by threatening to release a photo of her naked and tied up if she disclosed their relationship. Here's a look at possible legal implications:
Q: IS THERE AN INVESTIGATION?
A: Yes. The St. Louis circuit attorney's office said Thursday that it had launched a formal investigation to determine if Greitens committed crimes linked to the affair in 2015.
Circuit Attorney Kim Gardner initially said no complaint had been filed against Greitens and that her office had received no evidence. But later, she said an investigation was warranted.
Greitens and his wife released a statement Wednesday after St. Louis television station KMOV reported on the affair. He acknowledged being "unfaithful" in his marriage but denied blackmailing the woman to stay quiet.
Q: IS THE FBI INVESTIGATING?
A: An attorney for the woman's ex-husband says the attorney was interviewed by the FBI, but he did not say if the ex-husband had also heard from the agency. The FBI, as is its usual practice, declined to confirm whether it has opened an investigation.
The FBI does not need much — sometimes just media reports — to begin poking around, said Jeff Cramer, a former top federal prosecutor in Chicago. Once such an investigation has started, where it goes is often unpredictable.
"There is no elected official in the country who wants the FBI looking at their phone records and bank accounts," said Cramer, currently a managing director of investigations at Berkeley Research Group "They can be investigated at the beginning for one thing and end up being charged (later on) with another thing entirely."
Q. WHAT ABOUT BLACKMAIL?
A: The allegations, if true, would appear to fit the definition of blackmail, which involves threatening to reveal something to others that could potentially ruin the reputation of the person targeted or shatter the individual's relationships. This could include a secret or a compromising photo.
A conviction on a blackmail charge can carry years or even decades behind bars. However, blackmail can be difficult to prove, especially without third-party witnesses, Cramer said.
In Greitens' case, the woman's ex-husband alleges that Greitens photographed her and threatened to publicize the revealing image if she spoke about the affair.
"If there are no other witnesses," Cramer explained, "it becomes a 'he said, she said.'"
Q: WOULD IT BE A FEDERAL OR STATE CASE?
A: Because the affair seemed to happen in Missouri, jurisdiction would typically fall to state or local prosecutors. But Cramer said that does not mean federal authorities cannot make a case out of it. If any aspect of a crime involved sending an email, for instance, that alone can qualify the offense as federal because emails almost always bounce through servers across state lines. Using email to commit a crime can lead to a federal wire fraud charge, which carries a 20-year maximum sentence.
Sometimes local authorities actually prefer to have federal prosecutors take over. Federal prosecutors can bring more resources to a case. And in most federal judicial districts, U.S. attorney's offices get convictions in more than 90 percent of their cases.
Q: WHAT ABOUT OTHER POTENTIAL CRIMES?
A: In addition to blackmail, felony charges of illegal harassment are a possibility if the woman was threatened or assaulted or tied up against her will, said Peter Joy, a law professor at Washington University in St. Louis.
The key question is whether the activities were consensual.
"You can't just tie a person up (without consent). That in and of itself is an assault," he said. "On the other hand, if they were doing some kind of role play and she consented to it, that's a different story."
Whether the governor can be charged will be academic if the woman isn't willing to tell her version of events. If she doesn't come forward, Joy said, "this goes nowhere."
Q: COULD INVASION-OF-PRIVACY LAWS COME INTO PLAY?
A: Yes. That would also require the woman to file a formal complaint.
Missouri invasion-of-privacy laws include bans on people taking another person's picture without that person's permission in a place where people have an expectation of privacy, like a home or office. Under Missouri law, criminal invasion of privacy is usually a misdemeanor.
The woman's ex-husband, who, like the woman, has not been named, provided an audio recording he made to KMOV in which the woman gives details about an alleged sexual encounter she says she had with Greitens at his St. Louis home. She did not know her then-husband was recording their conversation.
Many states also have related eavesdropping laws that make it a crime under many circumstances to record audio without the permission of everyone being recorded. In Missouri, only one party has to be aware of and consent to the recording.
Q: COULD REVENGE-PORN LAWS APPLY?
A: More than 30 states have adopted laws prohibiting the circulation on social media or elsewhere of nude or sexually explicit photographs in acts of revenge against former sexual partners without the other person's permission, according to the Cyber Civil Rights Initiative, a group that advocates for such laws.
One of the few states without a revenge-porn law is Missouri, where such legislation failed last year. Some lawmakers recently sought to try again by introducing a similar bill. There's no federal law either, though some members of Congress are pushing for a nationwide revenge-porn law.
Applying new laws retroactively is normally considered unconstitutional, so even if those proposals were adopted, they almost certainly could not be used against Greitens.Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.