Nielsen is one of 12 Fundamentalist Church of Jesus Christ of Latter-Day Saints men, including Jeffs, charged following a massive 2008 raid on the sect's Yearning for Zion Ranch in Eldorado, Texas. His was the only case not to involve underage marriage.
Defense attorney David Botsford argued Nielsen's marriages were never intended to be legal unions, but rather celestial marriages that sect members believed would give the women, aged 65, 63 and 43, a path to heaven.
"It's all for a woman's eternal salvation," Botsford said, according to the Standard Times.
But prosecutor Eric Nichols said the unions fit the legal definition of marriage and were illegal.
"If it looks like a duck, walks like a duck, talks like a duck, what is it? It's a duck," he said. He presented sect documents seized in the raid as evidence and a former member testified to their authenticity. No victims testified.
The trial now moves into the sentencing phase, which prosecutors said they expect to complete Thursday. The jury will decide the sentence, as per Texas law. Prosecutors will present evidence of other so-called bad acts, which may not rise to the level of a crime but speak to the character of the accused.
Nielsen faces up to 10 years in prison.
In Nielsen's case, prosecutors plan to introduce additional raid evidence showing Nielsen performed marriage ceremonies joining Jeffs to 16- and 12-year-old girls, the Standard-Times reported.
Nielsen also allegedly witnessed 258 bigamous marriages, and has been involved in the marriage of 37 girls ages 12 through 16. Of those marriages, 29 were bigamous, the Standard-Times reported.
Nielsen initially pleaded no contest in the case and was sentenced to probation, but later withdrew his plea because a judge imposed stricter terms than those he'd agreed to and he wasn't able to transfer his probation to Colorado, where he has family.
Nielsen once served as the sect's president until Jeffs reclaimed the office from his jail cell early last year. He was reportedly excommunicated then, along with dozens of FLDS men and other top leaders.
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