JEFFERSON CITY, Mo.: Missouri Gov. Eric Greitens, a sometimes brash political outsider whose unconventional resume as a Rhodes scholar and Navy SEAL officer made him a rising star in the Republican Party, resigned Tuesday amid a widening investigation that arose from an affair with his former hairdresser.

The 44-year-old governor spent nearly six months fighting to stay in office after the affair became public in January in a television news report that aired immediately following his State of the State address. The probes into his conduct by prosecutors and lawmakers began with allegations stemming from the affair and expanded to include questions about whether he violated campaign-finance laws.

Greitens said his resignation would take effect Friday.

“This ordeal has been designed to cause an incredible amount of strain on my family — millions of dollars of mounting legal bills, endless personal attacks designed to cause maximum damage to family and friends,” he said in a brief statement from his Jefferson City office, his voice breaking at times.

He said he could not “allow those forces to continue to cause pain and difficulty to the people that I love.”

Lawmakers pressuring Greitens to step down included many Republicans, who feared that his troubles could jeopardize the GOP’s chances of defeating incumbent Democrat Sen. Claire McCaskill in a race considered essential to the party’s hopes of keeping control of the Senate.

The local St. Louis prosecutor’s office said it had reached a “fair and just resolution” on criminal charges against Greitens now that he’s leaving office. But the prosecutor said details would not be made public until Wednesday.

A St. Louis grand jury indicted Greitens on Feb. 22 on one felony count of invasion of privacy for allegedly taking and transmitting a photo of the woman without her consent at his home in 2015, before he was elected governor. The charge was dismissed during jury selection, but a special prosecutor from Kansas City is considering whether to refile charges and said Tuesday that her investigation is ongoing.

In April, the St. Louis prosecutor, Kim Gardner, 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.

Then less than two weeks ago, the Missouri Legislature began meeting in special session to consider whether to pursue impeachment proceedings to try to oust Greitens from office. A special House investigative committee had subpoenaed Greitens to testify next Monday.

Two people with close ties to Republican officials in Washington and Missouri told the Associated Press there was no coordinated effort to push Greitens out.

The governor’s brashness had alienated some GOP legislators even before his affair became public. Senate Leadership Fund President Steven Law said the resignation could help unify Missouri Republicans and free up money.

In January, the woman’s ex-husband released a secretly recorded conversation from 2015 in which she described the affair, which happened shortly after Greitens created an exploratory committee to run for office. The woman later told the House committee that Greitens restrained, slapped, shoved and threatened her during a series of sexual encounters that at times left her crying and afraid.

Greitens said the allegations amounted to a “political witch hunt” and vowed to stay in office. But a report from the House committee created a firestorm, with both Republicans and Democrats calling for his resignation.