A 38-year-old man from a polygamist sect sexually assaulted a teenager less than half his age at the Yearning For Zion Ranch, a prosecutor charged Wednesday to open the first criminal trial since the ranch was raided.

An attorney for defendant Raymond Jessop disputed the allegation, telling jurors there is no evidence Jessop sexually assaulted the girl in Schleicher County. The location is critical, since prosecutors must prove they have the jurisdiction to prosecute the alleged crimes.

Jessop was one of 12 members of the Fundamentalist Church of Jesus Christ of Latter Day Saints charged after authorities raided the ranch last year and swept 439 children into foster care. The children were later returned to their parents after an appellate court intervened, but documents and DNA seized during the raid resulted in criminal indictments on charges ranging from failure to report child abuse to sexual assault and bigamy.

All the men will be tried separately.

Both sides presented opening statements Wednesday evening in Jessop's case after 12 jurors — seven men and five women — were culled from a pool of 300, the largest ever called in this tiny county 200 miles northwest of San Antonio.

Assistant Attorney General Eric Nichols said Jessop was 33 when he had sex a 16-year-old girl, who later gave birth to a daughter. Under Texas law, generally, no one under 17 can consent to sex with adult. Nichols did not discuss the relationship between the two in his opening statement, but prosecutors have said in court documents the teen is one of Jessop's nine wives. Jessop has also been indicted on a bigamy charge that will be tried later.

"You will see evidence that establishes that this offense — the offense of sexual assault of (the teen) — occurred just down the road from this courthouse at the YFZ Ranch," Nichols told jurors.

Defense attorney Mark Stevens said prosecutors would not be able to show evidence of a crime occurring in Texas, and he urged jurors not to be distracted by the alleged polygamy or the religious beliefs Jessop and the church. Broadcast images of women from the church wearing prairie dresses and distinctive braids were impossible to ignore during the weeklong raid in April 2008.

"We don't try people because of their hairstyles or their clothes. We don't try people because of their religious practices," Stevens said. "We try people based on evidence, facts and proof."

Testimony in the case is scheduled to begin Thursday. Nichols had previously said the trial would take about two weeks. Prosecutors have prepared to call dozens of witnesses, including law enforcement officials, child welfare workers and church members.

The FLDS is a breakaway sect that is not recognized by the Mormon church. It has historically been based along the Arizona-Utah border, but church members bought a 1,700-acre ranch outside Eldorado about six years ago and began building log cabin-style homes and a four-story limestone temple that is visible from the highway that run's through the town of about 2,000 people.

Sect Leader Warren Jeffs was arrested in 2006 and convicted as an accomplice to rape in Utah for arranging an underage marriage there. He awaits trial on similar charges in Arizona before he can be tried for sexual assault of a child and bigamy in Texas.

Fearing possible prosecution for underage marriages, Jeffs allegedly advised Jessop not to take the 16 year old to the hospital even though she was struggling for days in child labor. One of Jeffs' daughters allegedly married Jessop at age 15 and is the focus of the separate bigamy indictment.

The Mormon church, Church of Jesus Christ of Latter-day Saints, renounced polygamy more than a century ago.