SALT LAKE CITY — The Utah Court of Appeals has thrown out one of seven rape convictions for a polygamist sent to prison for his sexual relationship with a 17-year-old girl he considered his bride.

The appeals court found prosecutors failed to show one of the incidents occurred in Utah instead of Texas, where Kain Blackwing brought the teenager for a time in 2014. The panel of three judges did not consider Blackwing’s request for a new trial, finding he didn’t file the proper paperwork for that portion of his appeal, according to the opinion released over the weekend.

While teaching martial arts and survival skills to the 17-year-old girl and her boyfriend, Blackwing convinced the girl to leave her boyfriend and move in with him, court documents say. Prosecutors argued Blackwing’s role of special trust, combined with the teenager’s age, meant she was not capable of consenting to sex with him under Utah law.

As the girl began “spending more time with Blackwing, he taught her about ‘Shen living,’ telling her that he was ‘a Shen lord’ and that ‘Shen can have multiple women,’” Judge Kate Appleby wrote in the opinion. “In fact, Blackwing had two putative wives, who called him ‘My Lord.’”

The case is one in a series involving the now 51-year-old Blackwing. He has separately pleaded not guilty to soliciting murder, a first-degree felony, and other charges alleging he plotted to kill a 14-year-old girl he was later convicted of sexually abusing.

Prosecutors filed the charges in West Jordan’s 3rd District Court after his wife, Raven Blackwing, and another woman dressed like ninjas — in black clothing and masks — broke into a West Jordan house where the girl was staying, wielding a gun, knife, syringes and poison. Raven Blackwing was later sentenced to prison for her role and the other woman to probation.

Raven Blackwing has pleaded not guilty to an additional 11 felony charges for allegedly participating in the assaults of the 17-year-old.