The trial of Chad Daybell, the man accused of killing his two stepchildren and late wife in a widely followed series of murders involving "doomsday" religious beliefs, began with jury selection on Monday, months after Lori Vallow Daybell, the children's mother, was sentenced to life in prison.

Chad Daybell is charged with the murders of 7-year-old Joshua "JJ" Vallow, Tylee Ryan, last seen when she was 16, and his previous wife Tammy Daybell, who died of asphyxiation the year before. He also faces two counts of insurance fraud for collecting on his late wife's life insurance.

The cases have drawn international attention for the bizarre "doomsday" religious beliefs espoused by Chad Daybell and Lori Vallow Daybell that were cited by prosecutors as a factor in the murders.

If convicted, Chad Daybell could receive the death penalty. Prosecutors successfully argued in 2021 that the "especially heinous, atrocious or cruel" nature of his crimes should make him eligible for capital punishment.

Last summer, Lori Vallow Daybell was sentenced to life in prison without the possibility of parole for her role in her children's deaths. She was convicted of first-degree murder and conspiracy to commit murder in the deaths of both children, and received an additional 10-year prison sentence on a grand theft charge.

Chad Daybell and Lori Vallow Daybell were originally slated to be tried together. The court granted a motion filed by Chad Daybell's attorney to sever the two trials last year, in the interest of preventing a jury from confusing evidence between the two cases, and as a privilege of Daybell's against "self-incrimination."

In a motion attempting to strike the death penalty from the case, Daybell's attorney John Prior argued that Lori Vallow Daybell was the "most culpable party" in the murders. He quoted prosecutors statements that she "manipulated Chad through emotional and sexual control," and that he would not "act without Lori saying so."

Jury selection begins days after 7th District Court Judge Steven Boyce issued a gag order preventing Prior from speaking publicly about the case after Prior gave an exclusive interview about the case to local TV station KIVI-TV.

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The remains of the two children were found on Chad Daybell's property near the small town of Salem, Idaho, in the summer of 2020 after police launched a search after JJ's grandmother reported she hadn't seen the little boy for months.

Chad Daybell was arrested in June of that year on suspicion of concealing and destroying evidence related to the children's deaths. Lori Vallow Daybell had been arrested that February. Authorities alleged the couple lied to investigators searching for the children before they fled the state and were found in Hawaii.

Investigators initially believed Tammy Daybell, Chad Daybell's then-wife of 30 years, died of natural causes in 2019. But suspicions were raised when Chad Daybell married Lori Vallow Daybell just two weeks later. An autopsy of Tammy Daybell's body later concluded that she died of asphyxiation.

About a year before the children's bodies were recovered, Lori Vallow Daybell's then-husband, Charles Vallow, was shot and killed by her brother Alex Cox in Chandler, Arizona, a Phoenix suburb where Lori Vallow Daybell lived with her children at the time. Cox claimed he killed Vallow in self-defense.

Charles Vallow was seeking a divorce from Lori Vallow Daybell at the time of his death. In court records, he claimed his wife believed she was "a god assigned to carry out the work of the 144,000 at Christ's second coming," and that she didn't want anything to do with her then-husband or son "because she had a more important mission to carry out."

Charles Vallow also said he took out a protection order against her after she threatened to kill him, saying she had "an angel there to help her dispose of the body."

After his killing, Lori Vallow Daybell moved to Idaho with the two children, where Chad Daybell lived and ran a publishing company alongside Tammy Daybell.

Chad Daybell wrote about his apocalyptic visions of "the decline and downfall of the United States" and an "upcoming foreign invasion of America" in multiple fictional books. In his 2017 autobiography, he described his religious beliefs as inspired by his visions and near-death experiences and his time in the The Church of Jesus Christ of Latter-day Saints.

Melanie Gibb, a friend of Lori Vallow Daybell, told investigators that Lori Vallow Daybell believed her children were "zombies" whose bodies could only be freed from a "dark" spirit by killing the "physical body." Gibb said Vallow and Daybell identified as members of the “Church of the Firstborn” and were on a mission to rid the world of "zombies."

Cybele Mayes-Osterman is a breaking news reporter for USA Today. Reach her on email at [email protected]. Follow her on X @CybeleMO.