PHOENIX — It's a case with so many dark twists and turns that started to unfold right here in Arizona.
We're talking about Lori Vallow Daybell and her husband Chad, both behind bars in connection to her children's deaths. But those aren't the only suspicious deaths connected to the couple.
A new 2-hour Dateline NBC special set to air Friday will feature a new interview with Samantha and Jason Gwilliam, the sister and brother-in-law of Tammy Daybell.
"I had no idea anyone was looking into them," Samantha says of Chad and Lori. "This was just me trying to figure out who is this woman that replaced my sister?"
Her sister, Tammy Daybell, was Chad Daybell's first wife. Tammy reportedly died in her sleep at their Idaho home in October 2019. Before that shock settled in, something else rattled the family.
Barely two weeks after Tammy’s death, Chad Daybell remarried with Lori Vallow in November 2019. We know now that her children, Tylee Ryan and J.J. Vallow, were already missing by this point in the timeline.
"I was told her name was Lori Ryan," Jason tells Keith Morrison. "I was told that she was an amazing person. That he couldn’t wait to introduce me."
"I was trying to figure out who Lori Ryan was," Samantha adds. "But then I found out her name wasn’t really Lori Ryan - it was Lori Vallow. And her husband didn’t die from a heart attack. He was shot."
Lori’s fourth husband, Charles Vallow, was shot and killed by Lori’s brother in Chandler back in July 2019. That case is still under investigation and charges are expected.
Lori moved from Arizona to Idaho with her kids in September 2019. The kids disappeared within days of the move, but authorities wouldn't start investigating until other relatives asked for a welfare check shortly after Thanksgiving.
As the searched heated up for Tylee and JJ, Chad and Lori were in Hawaii, dodging questions. Lori was ultimately arrested for failing to produce her children in February 2020 and extradited back to Idaho in March 2020.
Chad Daybell was arrested three months later after the children's bodies were discovered gruesomely buried in his backyard.
"One warning bell after another," Samantha says. "There’s something seriously wrong here."
Chad and Lori are both facing conspiracy charges connected to the children’s death in a joint trial set for this summer.
Tammy’s death is now considered suspicious and the Idaho Attorney General’s Office is investigating Lori and Chad for her death.
Dateline NBC's Mommy Doomsday airs Friday at 8 p.m., only on 12 News.