Judge Thomas Solka said the case against 62-year-old Karen Kirby came down to witness credibility, a battle that she lost. Now she is facing up to 15 years in prison.
Kirby represented herself this week in court, calling Calvin Martz as her sole witness, choosing not to testify on her own behalf.
Martz claimed Kirby's daughter was his wife under God and had returned to their home to reside there permanently with the two. He also denied they had secretly and physically restrained the victim from leaving the cabin and contacting the authorities during a May 6 raid by Michigan State Police.
Several officers from the Michigan State Police and Marquette Police Department, as well as the victim, testified for the prosecution. The victim says Martz had been sexually assaulting her since the age of 14 when he claimed her as his wife.
She had intended to pay a short visit to her mother and then was confined with the two for several days. The victim claimed she was physically restrained by both Martz and Kirby on the day of the raid.
Assistant Prosecuting Attorney Judd Spray says the verdict will give the victim a chance to move on.
"The evidence was overwhelming that she (Kirby) was a participant and an aide and abettor in forcibly and secretly confining during authority's efforts to locate her (victim)," said Spray.
Calvin Martz' sentencing will be on Friday.