BOISE, Idaho — The trial of a man charged with the deaths of his wife and his girlfriend’s two youngest children is set to begin in Idaho this week, serving as a second act in a bizarre case that has drawn worldwide attention and already resulted in a life sentence for the mother of the children.

Chad Daybell’s trial is expected to last up to 10 weeks, with jury selection scheduled to get underway in Boise on Monday. The 55-year-old self-published author is charged with three counts of first-degree murder for the deaths of Tammy Daybell, 7-year-old Joshua “JJ” Vallow and JJ’s big sister, Tylee Ryan, who was last seen a few days before her 17th birthday.

The younger children’s mother, Lori Vallow Daybell — who married Chad Daybell shortly after the deaths — was found guilty last year and sentenced to life in prison without parole.

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.

The children’s bodies were found buried in Chad Daybell’s eastern Idaho yard in the summer of 2020.

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 in Arizona in July 2019 and the brother told police it was in self-defense.

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, 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.