'Dateline': Keith Morrison Says 'It's Not Over' in Dramatic Lori Vallow Special Preview

NBC is airing a new episode of Dateline Monday at 10 p.m. ET, and the hour-long episode will include the first-ever interview with Melanie Gibb, a former friend of Lori Vallow. The remains of Vallow's two children were found in the backyard of the home owned by Vallow's husband, Chad Daybell, on June 10. The children, 16-year-old Tylee Ashlyn Ryan and 7-year-old J.J. Vallow went missing from Rexburg, Idaho in September 2019. In a preview for the special, "What Happened to JJ and Tylee," journalist Keith Morrison noted the case is "not over" yet.

Gibb told Morrison that Vallow and Daybell have "deception" in them. "l saw him as the hand and her as the puppet on that hand. They were both, like, gasoline and fire - equally destructive to each other," she told Morrison, adding that the two both lie. "And so, that was their common thread, that they were really good lying to each other. [It] seemed a good fit, for them to be like that with each other."

Tylee was last seen on Sept. 8, 2019 in Yellowstone National Park, while J.J. was last seen alive on Sept. 23 outside Kennedy Elementary School in Rexburg. Relatives began getting concerned about the two after they went several weeks without hearing from them. In November, police first questioned Vallow. She and her husband Daybell first lied to police, telling them they were staying with Gibb in Arizona, where the family lived before they moved to Idaho. Gibb told police this was not the case. She also told police Vallow and Daybell wanted her to lie about J.J.'s location.

Vallow was arrested on Feb. 20 in Kauai, Hawaii for desertion and nonsupporting her children. She was extradited to Idaho and arrived there on March 5. She is still in jail on $1 million bail and has not entered a plea. On June 9, police searched Daybell's home, where they found the remains of two children. After the bodies were identified as the children, Daybell was arrested on two felony counts of destruction, alteration or concealment of evidence. Daybell pleaded not guilty.

The case caught national attention due to the other mysteries surrounding Daybell and Vallow. In July 2019, Vallow's estranged husband and J.J.'s father, Charles Vallow, was shot and killed in Phoenix by Vallow's brother Alex Cox, who claimed self-defense. Cox died from a blood clot in December 2019. In October 2019, Brandon Boudreaux, the husband of Vallow's niece Melanie Boudreaux, was killed in his driveway from a vehicle registered to Charles. That same month, Daybell's then-wife Tammy Daybell was attacked by someone shooting a defective paintball gun. She died on Oct. 19 from "natural causes" and no autopsy was performed. Two weeks after Tammy's death, Vallow and Daybell married, prompting police to investigate Tammy's death.

Gibb previously said she discovered a letter in which Vallow predicted Charles' death. He "was supposed to die according to the visions she had of him dying and she was greatly disappointed when he didn't," Gibbs wrote, according to the East Idaho Times. "Chad and Lori were so anxious to be together that Chad devised a plan and called Lori to let her know that Charles was taken over by an unclean spirit and was no longer Charles anymore. These unclean spirits would later be called Zombies." Gibbs also theorized that Daybell might have manipulated Vallow, but did not claim Vallow played a part in Charles' "troubling" death.