Jury selection is set to begin Monday in the trial of Chad Daybell, who is charged in the deaths of his wife, Tammy Daybell, and then-girlfriend Lori Vallow’s two youngest children, 7-year-old Joshua “JJ” Vallow and Tylee Ryan, 16.

The bizarre case drew national attention after JJ’s grandparents reported the children missing in 2019, weeks after each was last seen, and shortly after the death of Tammy Daybell, which was initially attributed to natural causes. The children’s bodies were found burned and buried in the Daybells’ backyard in eastern Idaho in 2020.

Chad Daybell’s trial is expected to last up to 10 weeks. The 55-year-old self-published author is charged with three counts of first-degree murder.

The children’s mother, Lori Vallow Daybell, who married Chad Daybell just weeks after his wife’s death, was convicted last year by an Idaho jury and sentenced to life in prison without parole in the case, in a trial that laid bare the couple’s bizzare, doomsday-focused beliefs.

The couple claimed they could tell if people had been possessed by dark spirits that could turn them into “zombies,” former friend Melanie Gibb testified in court. They believed the only way to get rid of a zombie was to destroy the possessed person’s body by killing them.

Chad Daybell also is charged with insurance fraud in connection with Tammy Daybell’s death and two counts of conspiracy to commit first-degree murder and grand theft by deception in the children’s deaths.

If convicted, he could face the death penalty.

Daybell has pleaded not guilty. Last week, his attorney John Prior told KIVI-TV in Boise that Daybell is ready to go forward with the case and “wants to tell his story.”

Two days later, 7th District Judge Steven Boyce issued a gag order barring any of the attorneys or parties in the case from talking about it until after jury selection and opening statements.

Chad and Lori Daybell originally were scheduled to stand trial together, but in 2022 Prior asked the court to split the cases, saying the co-defendants will have “mutually antagonistic defenses.” The legal term generally means a jury would have to disbelieve one defendant in order to believe the other.

“Our version of the facts of this case will differ greatly from what Ms. Vallow and her legal counsel are going to be presenting,” Prior told the judge, who later agreed to split the cases.

The grim case began in the fall of 2019, after extended family members noticed Lori Vallow’s two youngest kids seemingly had disappeared and prodded law enforcement to launch a search. The subsequent months-long investigation spanned several states and took several grim and unexpected turns.

Lori Vallow and Chad Daybell were having an affair when both of their spouses died unexpectedly, investigators learned. Vallow’s husband was shot to death by her brother, Alexander Cox, in Arizona in July 2019 and the brother told police it was in self-defense. She was extradited to Arizona following her Idaho conviction, where she faces two charges of conspiracy to commit murder in the death of her husband and in the case of Brandon Boudreaux, her niece’s ex-husband, whom authorities say was shot at by Cox. Cox died suddenly in December 2019.

Tammy Daybell died in her sleep in November 2019, the untimely death first chalked up to natural causes but later determined to be from asphyxiation, according to an autopsy. Lori Vallow and Chad Daybell married just two weeks after Tammy Daybell died, surprising family members and authorities.

The couple’s friends later told detectives that the pair also held unusual religious beliefs, including that they had been reincarnated and were tasked with gathering people before a biblical apocalypse.

Lori Vallow Daybell referred to her two youngest kids as zombies before they vanished in September 2019, one friend would later testify during her trial, Gibb testified.

Prosecutors say Lori and Chad Daybell espoused those doomsday-focused beliefs to justify the deaths of her kids and his wife, but it was all part of a scheme to eliminate any obstacles to their relationship and to obtain money from survivor benefits and life insurance.