Former prosecutor and Fox Nation host Nancy Grace said that she fears the children of Idaho woman Lori Vallow are either "tucked away with some doomsday cult or they're dead."

Vallow, 46, was extradited to her home state after being arrested in Hawaii last month and charged with two counts of felony abandonment. Her two children, 17-year-old Tylee Ryan and 7-year-old JJ Vallow, have been missing since September.

On Fox Nation's "Crime Stories," Grace and her panel of experts delved into Vallow's seemingly bizarre background.

"She is called 'cult mom' because she has, within a few weeks, after her fourth husband was shot dead, she remarries to Chad Daybell," said Grace, in reference to Vallow's current husband, who wrote fictional apocalypse-themed books.

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"Chad Daybell seems to be some kind of a leader of a small group that included Lori Vallow and her niece Melody and a number of their friends," added private investigator Rich Robertson. "They seem to be a subgroup of the larger kind of fringe, prepper group."

Grace observed that she discovered, in divorce papers filed by Vallow's deceased husband, Charles Vallow, that she was alleged to have an interest in "end of days" fantasies.

"In his divorce papers, he says... that Lori Vallow told him she's already married and eternally sealed with the ancient prophet Moroni, which is part of the Mormon religion. And that she has been chosen to lead the chosen 144,000 people that are going to get to go to Heaven."

Nate Eaton, a reporter for EastIdahoNews.com, has also closely followed Vallow's case.

"Charles was so worried that he went before the judge and said, 'I want custody of the kids because my wife's talking like this -- that she is a goddess -- that this is her mission, that she is sent here to Earth to usher in the second coming of Jesus Christ and the world will end on July 22nd of this year.'"

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"So a lot of people wonder if she was preparing for this Second Coming by doing something with her children by ... maybe a dramatic action so that they would be prepared for the Second Coming," said Eaton.

"I think in the coming days, as court documents come out and as we get ready for the next hearing, we'll be learning more about what she told others and what investigators know as well."

Grace said that her experience prosecuting and covering cases of mothers who killed their children makes her fear that Vallow may be exhibiting the characteristics of those killers.

"Many of them do so for misplaced religious beliefs, such as: 'I don't want [children] to live in a world of sin,'" she said. "All along, I've secretly believed... that there's a very good chance she's got them tucked away alive because she seems so unconcerned about where they are or their safety."

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