A member of a polygamist sect at the centre of a police raid last year that swept more than 400 children into state custody goes on trial Monday in the sleepy west Texas town of Eldorado.

Attorneys will begin culling the largest jury pool ever called in Eldorado to try to find 14 people in a county of 2,800 who can set aside what they've heard about the sect.

Raymond Jessop, 38, will become the first man from the Yearning for Zion Ranch to go on trial here. He is charged with sexual assault of a child — an underage girl he allegedly married first — and faces up to 20 years in prison if convicted. He is also charged with bigamy for allegedly marrying a second underage girl but will be tried on that charge separately.

In all, 12 men from the sect have been charged with crimes ranging from failure to report child abuse to bigamy and sexual assault at the ranch, where women and girls wear braids and pastel prairie dresses. They have all denied wrongdoing.

The cases began after a woman in Colorado allegedly called a Texas domestic abuse hotline in March 2008 and pretended to be a teenage girl with a much-older husband who raped and beat her.

State authorities swooped in, taking 439 children away from their sheltered lives and confiscating hundreds of boxes of documents and family photos to build their case. The Texas Rangers have acknowledged the hotline information was false, but the caller has never been charged.

Seating a 12-person jury and two alternates for Jessop's case might be a difficult because most residents of the tiny ranching community know each other, and national and international media coverage made the April 2008 raid impossible to ignore.