(NewsNation) — As the trial of Lori Vallow gets underway in Idaho, the doomsday religious beliefs allegedly connected to a triple murder she is accused of have come to light.

Prosecutors charged Lori Vallow Daybell and her husband, Chad Daybell, with conspiracy, murder and grand theft in connection with the deaths of Vallow’s two youngest children: 7-year-old Joshua “JJ” Vallow and big sister Tylee Ryan. Prosecutors also have charged the couple in connection with the October 2019 death of Chad Daybell’s late wife, Tammy Daybell.

The case gained attention for the couple’s doomsday beliefs and strange worldview that detectives think may have influenced Vallow and Daybell.

Cult experts say Daybell, who followed a group called “Preparing a People,” took the organization’s teachings to an extreme. He would talk about “zombies,” souls leaving bodies and told his followers that the world was going to end on July 22, 2020.

Rick Allen Ross, founder and executive director of The Cult Education Institute, said doomsday cults are very common.

“The grandparents contacted me early on, they were very confused,” Ross said. “They could not understand what Lori Vallow was doing, why she was doing it and the power that Chad Daybell had over her.”

Despite doomsday cults being common, Ross said cults committing violent crimes like murder are very rare.

“They use doomsday predictions to essentially leverage control to make the people that are following them feel that it is urgent, and the only place of safety is with them,” Ross said. “And they become more dependent upon the leader to make value judgments for them to make choices for them.”

Ross said he thinks that’s what happened to Vallow.

“I think Chad Daybell exploited her religiousness and hold her in with his books and his sermons,” he said. “He being a Mormon himself and a graduate of BYU, you could see it almost as affinity fraud.”

Ross said Daybell’s wife ultimately became an obstacle to him.

“She was not that enthusiastic about his books and his career,” he said. “And so he benefited from a half a million dollars from her life insurance policy.”

As Vallow and Daybell are to be tried separately, NewsNation senior national correspondent Brian Entin says there is a chance one might testify against the other.

“Chad Daybell’s lawyer has been sitting inside the courthouse, watching the jury selection process and plans to watch the entire trial,” Entin said. “So clearly, he’s going to have an advantage here. He’s gonna watch how everything plays out with Lori’s trial, and then his trial comes up next.”