By Matthew Waller
MIDLAND, Texas (Reuters) - Were the "spiritual" marriages of a former leader of a breakaway Mormon sect to multiple women true marriages under Texas law?
That's the question that a jury of five women and seven men will have to answer in the bigamy trial that started this week of a former president of the polygamist Fundamentalist Church of Jesus Christ of Latter Day Saints.
Wendell Loy Nielsen, 71, is charged with three counts of bigamy, a rarely prosecuted crime.
Prosecutors said in opening arguments on Thursday in Midland, Texas that religious documents will show that Nielsen was living with women and claiming to be married, in violation of Texas bigamy laws.
"You will see documents showing that they became a part of the family unit. They were held out by the parties as being married," prosecutor Eric Nichols said.
But defense lawyer David Botsford said the evidence would show that the marriages by church members were not the kind of marriage covered in the bigamy law.
"The state cannot prove that celestial marriage or spiritual marriage violates the bigamy statute," Botsford said. "Apply the law and the facts that the judge gives you. Those marriages are spiritual unions."
Prosecutors say that Nielsen married two women on the same day in February 2006. According to a report filed in 2010, prosecutors believe Nielsen "married" 34 women in addition to his legal wife, although he is only being charged with three counts of bigamy.
The sect Nielsen headed has practiced polygamy ever since breaking away from the mainstream Church of Jesus Christ of Latter-Day Saints -- also known as the Mormon church -- in the late 1800s. The Mormon church has condemned the sect, which teaches that for a man to be among the select in heaven he must have at least three wives. The sect has an estimated 10,000 followers in North America.
Nielsen was one of 12 men indicted for crimes including child sexual assault, bigamy and performing an illegal marriage after an April 2008 law enforcement raid on the sect's Yearning for Zion Ranch in Texas to check on accusations of sexual assault.
Ten of the men have been convicted, including church leader Warren Jeffs, who was found guilty last year of sexually assaulting two underage girls he wed as spiritual brides, the younger of whom was 12 years old.
Jeffs is in prison in protective custody in Palestine, Texas, for life plus 20 years. But he still exerts influence in the sect through his brothers, sends out prophetic messages to public officials and has taken out advertisements in newspapers across the country.
Nielsen was the president of the sect's corporation in Utah until he stepped down so Jeffs, who was still the supreme leader, could assume the presidency early in 2011.
This is the first bigamy case of the 12 men to go to trial. Two have pleaded no contest to bigamy charges before and received seven and eight years in prison.
Bigamy is a third-degree felony punishable by two to 10 years in prison and up to a $10,000 fine.
Nichols told jurors that he anticipates that former members of the sect will testify and that he will produce documents seized in the 2008 raid.
(Editing By Corrie MacLaggan and Greg McCune)