San Angelo, Texas (CNN) -- The state and defense rested their cases in the penalty phase of convicted polygamist sect leader Warren Jeffs' trial Monday.
The defense did not call any witnesses. Closing statements are scheduled to start at 10:30 ET Tuesday morning. Each side will have 30 minutes. Deliberations are expected to begin immediately thereafter.
Jurors weighing punishment for Jeffs heard audio recordings earlier Monday that prosecutors say show he had sex with underage girls and encouraged group sex.
At times difficult to hear, one of the tapes recorded sounds of two people apparently engaging in intercourse. Other recordings captured Jeffs instructing what prosecutors say were underage girls in how to please him. Girls could be heard giggling in the background.
Prosecutors also presented evidence that Jeffs knew he was wanted by federal authorities and was aware that if people outside his community knew about his behavior, they would be extremely upset.
FBI Special Agent John Broadway testified that Jeffs ordered the destruction of various discs and transcripts three days after an arrest warrant was issued for him on June 10, 2005. The polygamist sect leader established "houses of hiding," allegedly with young girls for him to marry, Broadway said.
The FBI agent also read from a priesthood record, in which Jeffs allegedly wrote: "Things are happening so quickly. There is an even younger girl that the Lord wants me to take. She is 13. For some reason the Lord is sending me these girls that can be worked with."
Jeffs also wrote: "If the world knew what I was doing, they would hang me from the highest tree," according to evidence presented in court.
Jeffs was convicted last week on two counts of sexual assault on a child.
Jeffs' nephew and niece had testified Saturday about the alleged abuse they suffered at his hands.
Brent Jeffs, 28, told jurors that his uncle raped him when he was 5 years old.
"He began to tell me that we were going to do God's will," he said Jeffs told him. "This is between me, you and God."
Three jurors wiped tears from their eyes as Brent Jeffs spoke, his voice breaking with emotion.
Several also cried during the niece's testimony, in which she described an incident that allegedly occurred between her and Jeffs when she was 8 years old.
"He made me sit on his lap," she testified, and did "inappropriate things to me."
She was crying so hard at one point that the prosecutor stopped questioning. Neither side pressed her for details. CNN is withholding the niece's name because she is the alleged victim of a sexual assault. Brent Jeffs has published a book about his life and has previously been public about the allegations against his uncle.
Jeffs, the leader of the Fundamentalist Church of Jesus Christ of Latter-day Saints, faces a maximum sentence of life in prison on his conviction of sexually assaulting a 12-year-old and a 15-year-old who were his "spiritual wives."
He 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 could face a sentence of two to 20 years.
The charges were filed after a 2008 raid on a ranch his church operates near Eldorado, Texas.
During the first day of the sentencing hearing Friday, Jeffs said he objected to the introduction of items seized in the raid and documents that should get "religious protection."
He requested to be excused from the sentencing phase to avoid hearing his religion degraded.
"I am God. Cease. Do not present my holy ways as a thing of naught," the self-proclaimed prophet said before he left court Friday. "Hear my warning as a full awakening. Let my holy way be of freedom."
Deric Walpole, one of the defense attorneys Jeffs had fired earlier in trial, is representing him during the penalty phase.
Jeffs represented himself during the guilt-innocence phase of the trial. He was silent during most of his 30-minute closing argument Thursday, mumbling at one point, "I am at peace."
Monday was not the first time jurors heard audio recordings. Texas prosecutors rested their case last week after playing a key piece of evidence: A 20-minute audiotape that began and ended with a man saying a prayer.
Prosecutors alleged that the recording was of Jeffs' sexual assault of a then-12-year-old girl in the presence of three other "wives."
The girl had grown up at Jeffs' Yearning for Zion ranch, authorities said.
Prosecutors showed the jury a photo of her with her arms around Jeffs, and a marriage certificate that listed the girl's age as 12 at the time.
Jurors also 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' 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.
In Session's Beth Karas and Grace Wong contributed to this report.