FILE - In this Jan. 9, 2017 file photo, Missouri Governor Eric Greitens gives his inaugural address from the steps of the capitol in Jefferson City, Mo. Greitens, a sometimes brash outsider whose unconventional resume as a Rhodes Scholar and Navy SEAL officer made him a rising star in Republican politics, abruptly announced his resignation Tuesday, May 29, 2018, after a scandal involving an affair with his former hairdresser led to a broader investigation by prosecutors and state legislators. The resignation takes effect Friday. (AP Photo/Orlin Wagner File)
FILE - In this Jan. 9, 2017 file photo, Missouri Governor Eric Greitens gives his inaugural address from the steps of the capitol in Jefferson City, Mo. Greitens, a sometimes brash outsider whose unconventional resume as a Rhodes Scholar and Navy SEAL officer made him a rising star in Republican politics, abruptly announced his resignation Tuesday, May 29, 2018, after a scandal involving an affair with his former hairdresser led to a broader investigation by prosecutors and state legislators. The resignation takes effect Friday. (AP Photo/Orlin Wagner File) Credit: Orlin Wagner

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 on 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 on Friday.

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.