Although the agreement between Gardner and Greitens resolves the tampering charge, a separate investigation will continue into allegations of wrongdoing by Greitens during his affair with his hairdresser in 2015.
In April, the local St. Louis prosecutor's office charged Greitens with another felony, alleging that he improperly used the donor list for a charity that he had founded to raise money for his 2016 campaign. Jackson County Prosecutor Jean Peters Baker is leading that probe. "I do not celebrate his downfall, but I am hopeful that we can begin a new chapter with Governor Mike Parson", she said.
"I will walk off the battlefield with my held high", Greitens said.
The 44-year-old Greitens was a political novice when elected governor in 2016.
Greitens' resignation also allows him to avoid the distinction of becoming the first Missouri governor to be impeached. The committee, led by chairman Jay Barnes, R-Jefferson City, has released two reports during its ongoing investigation.
On May 17, Greitens suggested to a crowd of supporters gathered for an agricultural event that he wouldn't give up.
Greitens had been facing a felony charge and possible impeachment during an investigation of claims that he tried to dodge the state's campaign disclosure laws and to blackmail a former lover.
"I am not ideal".
"I think what folks need to know is it's now time to leave the governor alone and let him and his family heal", Martin said.
Roe said Greitens had been prepared for a two-stage fight. His brashness had alienated some GOP legislators even before his affair became public in January.
In February, St Louis prosecutors indicted Greitens on a felony invasion-of-privacy charge in connection with the incident, which he said was consensual.
The hair stylist alleged that Mr Greitens had taken a photo of her when she was partially nude without her permission and threatened to release the image if she ever told anyone about the affair.
At a news conference Tuesday afternoon, Greitens denied the allegations against him but said it had become too hard for him to continue in the job.
Specifically regarding any deals we made with Governor Greitens' attorneys, no deals were made by my office.
Missouri's attorney general, Josh Hawley, a Republican, however backed Gardner's charge last month and said: "These are serious charges - and an important reminder that no one is above the law in Missouri".
Greitens was accused of taking a photo of his lover in a state of undress without her consent and making it accessible by computer to use as retaliation should she divulge their relationship.
When he steps down Friday, the former Navy SEAL officer will be conceding political defeat amid allegations of sexual misconduct and campaign violations while still defiantly asserting that he's done nothing worthy of being forced out of office.