Read more about this story from CNN affiliate KSTU.

(CNN) -- Court officials have released the chilling audiotapes that prosecutors say depict convicted child rapist Warren Jeffs training the girls he claimed were his "spiritual wives" to have sex with him.

The audiotapes, that were key pieces of evidence in Jeffs' trial, brought some jurors to tears during Jeffs' trial.

Last week, a Texas jury sentenced Jeffs to life in prison for aggravated sexual assault of a 12-year-old girl and 20 years in prison for the sexual assault of a 15-year-old girl.

Jeffs, 55, had perverted his position as the head of the Fundamentalist Church of Jesus Christ of Latter-day Saints to "satisfy his own personal appetites and desires," prosecutor Eric Nichols said.

Jeffs talks about those desires on audiotapes that authorities seized from his car and the church's Yearning For Zion Ranch compound in Eldorado, Texas.

The tapes, that were obtained by many media outlets including the Salt Lake Tribune and CNN affiliate KSTU on Thursday, contain what prosecutors say is evidence of Jeffs instructing underage girls to have sex with him.

At one point, Jeffs is heard saying God instructs "for quorums of wives to be with me, to assist me. To be a comfort. Yes, even physically."

Several times, Jeffs refers to having sexual relations with him as "heavenly sessions," and he instructed the young ladies that they also "must assist each other" during these sessions.

"You have to know how to be excited sexually," Jeffs said. "The Lord has intended that my ladies, all of my ladies be trained."

During Jeffs' trial, an FBI agent read from a journal that Jeffs kept in which prosecutors say prove he knew his behavior would be frowned upon.

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.