SAN ANGELO — A Texas jury convicted polygamist sect leader Warren Jeffs of child sexual assault Thursday in a case stemming from two young followers he took as brides in what his church calls "spiritual marriages."

The 55-year-old head of the Fundamentalist Church of Jesus Christ of Latter Day Saints stood stone-faced as the verdict was read.

Jeffs, who acted as his own attorney, faces up to life in prison. The jury went immediately into sentencing proceedings. They had deliberated on a verdict for more than three hours.

Prosecutors used DNA evidence to show Jeffs fathered a child with a 15-year-old girl and played an audio recording of what they said was him sexually assaulting a 12-year-old girl. They also played audio recordings in which Jeffs was heard instructing young women on how to please him sexually.

Jeffs has claimed he was the victim of religious persecution. The FLDS, which has at least 10,000 members nationwide, is a radical offshoot of mainstream Mormonism. The church believes polygamy brings exaltation in heaven and that Jeffs is God's spokesman on earth.

Police had raided the group's remote West Texas ranch in April 2008, finding women dressed in frontier-style dresses and hairdos from the 19th century as well as seeing underage girls who were clearly pregnant. The call to an abuse hotline that spurred the raid turned out to be a hoax, and more than 400 children who had been placed in protective custody were eventually returned to their families.

But authorities brought charges against several men from the group, with Jeffs by far the highest-profile defendant.

Jeffs stood mute and expressionless, staring at the floor, for all but a few seconds of the half hour he was allotted for a closing argument on Thursday. At one point he mumbled, "I am peace," and said no more.

The only noise in the courtroom was the creaking of wooden benches brimming with spectators.

Prosecutors said the case had nothing to do with his church or his beliefs.

"You have heard the defendant make repeated arguments about religious freedoms," said lead prosecutor Eric Nichols. "Make no mistake, this case is not about any people, this case is not about any religion. It is about one individual, Warren Steed Jeffs, and his actions."

Prosecutors relied heavily on information found during the raid on the compound and after a traffic stop in Nevada in 2006, when Jeffs was arrested. Much of the material was discovered in a vault at the end of a secret passageway in the temple and another vault in an annex building.

"You might have asked yourselves," Nichols said, "a lot of people may ask, why would someone record sex? … This individual considers himself to be the prophet. Everything he did, hour after hour, he was required to keep a record of that."

On one of the tapes played at the trial, Jeffs made a reference to "drawing close" or "being close," which authorities testified is how church members refer to sex. Two female voices said "OK."

"A good wife is trained for her husband and follows the spirit of peace," Jeffs was heard saying.

Another audio tape included Jeffs and the younger girl from a recording made in August 2006 at the Texas compound, according to testimony from Nick Hanna, a Texas Ranger involved in the 2008 raid.

Played in court, it was difficult to decipher, but Jeffs' and a female voice are heard. He says, "I perform this service in the name of Jesus Christ, Amen," then mentions the alleged victim by name. When she says something, he responds, "don't talk while praying." Several minutes of heavy breathing followed.

The jury wore headphones to better hear the recording and also followed a transcript. One female juror covered her face with her hand as she listened.

Jeffs represented himself after firing seven attorneys in the six months leading to the trial. He broke his courtroom silence with an objection marked by a nearly hourlong speech defending polygamy, and twice threatened the judge and the court with warnings of punishment from God.

He refused to cross-examine the state's witnesses, and delayed giving an opening statement until he began presenting his own defense. In that statement, he evoked images of the civil rights movement and mentioned former Mormon leader Joseph Smith Jr. He also asked the jury to remember constitutional guarantees of religious freedom.

The lone defense witness Jeffs called, church elder JD Roundy, spent about 10 minutes on the stand Thursday discussing FLDS history after 4½ hours of testimony Wednesday evening.

Jeffs failed three times to remove state District Judge Barbara Walther from the case, the last rejection coming even without a hearing. He claimed Walther was biased because she issued the warrant for the original raid and was frequently updated as it progressed.

Eleven other FLDS men were charged with crimes including sexual assault and bigamy. All seven of those who have been prosecuted were convicted, receiving prison sentences of between six and 75 years.