The first of a dozen polygamist sect members charged with abuse of women is set to stand trial today 18 months after agents raided the groupís remote ranch and carted off more than 400 children in the largest child custody case in American history.Raymond Jessop, 38, faces up to 20 years in prison if convicted of sexual assault of a child, a charge stemming from his alleged marriage to an underage girl in the Fundamentalist Church of Jesus Christ of Latter Day Saints. He will be tried later on a separate count of bigamy related to a second alleged underage bride.In all, 12 sect members have been charged with crimes ranging from failure to report child abuse to sexual assault and bigamy.Attorneys must cull from a pool of 300 people to try to seat 12 jurors and two alternates. Seating an impartial jury in this community of fewer than 1,900 voters may prove difficult, because most residents know one another and the April 2008 raid on the Yearning For Zion Ranch drew intense media coverage. Images of sect girls in pigtails and women in prairie-style dresses dominated the cable news networks for weeks after the raid.If lawyers canít come up with a jury from the initial pool, the trial could be moved to an adjoining county.Jessopís trial is expected to last two weeks, said Assistant state Attorney General Eric Nichols, who is prosecuting the case. The prosecutionís witness list has 59 people, including law enforcement and child welfare officials, two of Jessopís alleged wives and former FLDS members.Authorities have said little about the allegations against Jessop, but documents seized from the ranch indicate the assault charge stems from his alleged marriage to an underage girl. The girl later became pregnant and was in labor for several days in August 2005. But after Jessop consulted with sect leader Warren Jeffs, the girl wasnít taken to the hospital, allegedly out of fear that hospital authorities would discover her age and turn in Jessop.ďI knew that the girl being 16 years old, if she went to the hospital, they could put Raymond Jessop in jeopardy of prosecution as the government is looking for any reason to come against us there,Ē Jeffs wrote in a journal seized from the ranch.Jeffs was arrested in 2006 and later convicted as an accomplice to rape in Utah for arranging an underage marriage there. He faces similar charges in Arizona and is charged with bigamy and sexual assault of a child in Texas.One of Jeffsí daughters allegedly married Jessop the day after she turned 15. The bigamy charge against Jessop pertains to that alleged marriage.Under Texas law, generally, no one under 17 can consent to sex with an adult.Sect members, who believe polygamy brings glorification in heaven, historically have lived around the Arizona-Utah line, but the sect bought a ranch on the outskirts of Eldorado about six years ago. Hundreds of FLDS members, including many of the 439 children initially taken by child welfare authorities, have returned to the log cabin-style homes there.The sect is a breakaway of the Mormon church, which renounced polygamy more than a century ago.