Jury selection is set to begin Monday in Idaho for the death penalty trial of Chad Daybell, whose wife — "Doomsday Mom" Lori Vallow Daybell — was sentenced last year to life in prison without parole for murdering her two youngest children and conspiring to kill her husband's first wife.

Chad Daybell — a self-published writer of doomsday-focused fiction loosely based on Mormon teachings — faces the same charges as his wife, who told a friend she believed the kids, 7-year-old Joshua "JJ" Vallow and 16-year-old Tylee Ryan, had been taken over by evil spirits and turned into "zombies."

They were last seen alive in September 2019 and their bodies were found buried in Chad Daybell's yard in eastern Idaho the following summer.

JJ was asphyxiated with a plastic bag and duct tape over his mouth but Tylee's cause of death couldn't be determined because her body wasn't intact and arrived at the Ada County Coroner's Office in what the chief forensic pathologist testified last year were "three separate, sealed bags," TV station KTVB reported at the time.

Chad Daybell's first wife, Tammy Daybell, was found dead in her home in October 2019 with the cause also determined to be asphyxiation. Two weeks later, Chad Daybell married Lori Vallow, becoming her fifth husband.

During Lori Vallow Daybell's trial, her lawyer maintained there was no evidence tying her to any of the killings and suggested Chad Daybell, 55, and Lori Vallow Daybell's now-dead brother, Alex Cox, committed the killings, according to the Associated Press.

Defense lawyer Jim Archibald also said Lori Vallow Daybell was a loving, protective mother before meeting Chad Daybell, who convinced her that they'd been married in several previous lives and that she was a "sexual goddess" destined to help him save the world by gathering 144,000 followers so Jesus could return.

At her sentencing, Lori Vallow Daybell — who was repeatedly committed for mental health treatment to make her competent to stand trial — told the judge that she was regularly visited by the spirits of all three victims and that they were all happy and busy in the "spirit world."

"Jesus Christ knows that no one was murdered in this case," she said. "Accidental deaths happen. Suicides happen. Fatal side effects from medication happen."

But Judge Steven W. Boyce — who said killing one's own children was "the most shocking thing, really, that I can imagine" — told her she'd justified the murders by "going down a bizarre religious rabbit hole — and clearly you are still down there."