San Angelo, Texas (CNN) -- The Texas jury that found polygamist sect leader Warren Jeffs guilty Thursday of sexual assault will deliberate again to determine his punishment.

Jeffs, who represented himself after firing his defense team, remained stoic as the verdict was read.

Jurors will decide his fate after hearing additional witness testimony in the penalty phase of the trial, which began Thursday evening and will continue Friday.

The sect leader faces a maximum sentence of life in prison for his conviction of sexually assaulting a 12-year-old and a 15-year-old who were his "spiritual wives." The jury convicted him of two counts of sexual assault on a child -- charges that stemmed from a 2008 raid on a ranch his church operates near Eldorado, Texas.

Texas Attorney General Greg Abbott hailed the verdict and said prosecutors were seeking a life sentence for Jeffs.

"Here in the state of Texas, juries render tough, swift justice against anyone who would sexually assault a child," he said.

Before the verdict, witnesses showed jurors DNA evidence they said showed Jeffs conceived a baby with a 15-year-old child. And prosecutors presented an audio recording that they alleged documents Jeffs' sexual assault of a 12-year-old girl in the presence of three other "wives."

Abbott said attorneys were presenting new, "repulsive" evidence about the sect leader during the trial's penalty phase.

"I think it will confirm in (jurors') minds why they convicted the man and why they want to put him behind bars for a long time," he said.

Court adjourned about two hours after jurors reached a verdict Thursday. The trial was scheduled to continue at 10 a.m. Friday (11 a.m. ET).

Jurors deliberated for three hours and 45 minutes, starting Thursday afternoon. They sent out two notes during deliberations, requesting a CD player to listen to audio recordings and asking for the transcript of testimony from a witness.

Jeffs stood silently for most of his 30-minute closing argument Thursday -- the latest dramatic twist in a trial that included frequent objections and sermonlike speeches about religious freedom.

Jeffs stared at the table in front of him for most of his allotted block of time during closing arguments, as Judge Barbara Walther counted down.

He looked up at the jury when he reached the 20-minute mark, staring at each member. The jurors stared back.

Five minutes later, Jeffs mumbled, "I am at peace."

The leader of the Fundamentalist Church of Jesus Christ of Latter-day Saints spoke so quietly that people in the courtroom strained to hear him.

Prosecutor Eric Nichols warned jurors not to be swayed by Jeffs' frequent invocations of religious freedom as a defense.

The case, he said, has nothing to do with an attack on religion. Instead, it is about Jeffs and his actions, Nichols argued.

He showed pictures of Jeffs' alleged victims as he summed up his argument.

Jeffs began the hearing on Thursday -- the fifth day of his trial -- by asking for what he called constitutional protection because he represents a religious organization. The judge immediately denied his request.

The sect leader then questioned witness J.D. Roundy, a sect member who also had taken the stand for four hours the day before. He did not call additional witnesses to the stand.

On Wednesday, Texas prosecutors rested their case after playing a key piece of evidence for jurors: a 20-minute audio tape that began and ended with a man saying prayer. Prosecutors alleged that the recording documents Jeffs' sexual assault of a then-12-year-old girl in the presence of three other "wives."

The girl had grown up in Jeffs' Yearning for Zion ranch, clearing cactus and attending a Fundamentalist Church of Jesus Christ of Latter-day Saints school where Jeffs was principal, authorities said.

Prosecutors showed the jury a photo of her with her arms around Jeffs, and a marriage certificate which listed the girl's age as 12 at the time.

On Tuesday, the jury heard audio recordings that prosecutors said showed Jeffs instructing a 14-year-old and his other young "wives" on how to sexually please him in order to win God's favor.

Prosecutors said the 14-year-old was Jeffs' "spiritual wife" and conceived a child with Jeffs when she was 15.

Jeffs' trial started last week. He made no plea during his arraignment and remained silent for more than a day of the trial proceedings. But on Friday, he began repeatedly objecting -- at one point delivering an hourlong speech about his religious freedom "being trampled upon."

Jeffs could be sentenced to five years to life in prison on the charge of aggravated sexual assault regarding the alleged 12-year-old. For the other count, he would face a sentence of two to 20 years.

Jeffs' breakaway sect is believed to have about 10,000 followers. Their practice of polygamy, which the mainstream Mormon Church renounced more than a century ago, is part of the sect's doctrine.

The Texas legal proceedings began after about 400 children were taken from the sect's Yearning for Zion ranch in 2008. Jeffs was also charged with bigamy after the raid and is expected to be tried on that charge later.

Child protection officials said they found a "pervasive pattern" of sexual abuse on the ranch through forced marriages between underage girls and older men.

But the Texas Supreme Court ruled the state had no right to remove the children. The court also said the state lacked evidence to show that the children faced imminent danger of abuse. Most of the children were returned to their families, although some men at the ranch were charged with sexual abuse.

Jeffs was on the FBI's 10 Most Wanted list when he was arrested five years ago during a routine 2006 traffic stop in Las Vegas.

He was convicted in Utah on two counts of being an accomplice to rape for using his religious influence over his followers to coerce a 14-year-old girl into marrying her 19-year-old cousin. Afterward, he was sentenced to two consecutive prison terms of five years to life.

But in July 2010, the Utah Supreme Court overturned his convictions, ruling that the jury instructions were erroneous. Utah Attorney General Mark Shurtleff said last week Utah is prepared to retry Jeffs, depending on the outcome of the Texas case.

In Session's Christi Paul, Jim Kyle, Grace Wong and Keith Lovely Jr. contributed to this report.