The mother of Kyron Horman is convinced that his stepmom is not only somehow behind the 7-year-old's abduction, but that she was the one who planned it.
"Without a doubt," Desiree Young said Wednesday on the Today Show, when asked if she believes Terri Moulton Horman plotted his disappearance.
Kyron's biological father, Kaine Horman, has also said he thinks his estranged wife was involved in the boy's disappearance.
Looking back, Young says there were some red flags she missed before Kyron vanished from his elementary school June 4.
"Kyron became increasingly unhappy about not spending time with me. He wanted to come live with [me and his stepdad]," Young says. "Several times he would just break down and sob because he wanted to stay."
"To know I was four and a half hours away when he needed me to protect him," adds Young, "that's what I feel guilty for."
Though she says she has no evidence proving that the stepmom is responsible for Kyron's disappearance, Young tells PEOPLE, "In my heart of hearts, I have a feeling she had help. It's my feeling, my gut."
"She hired someone to kill her husband," she says, referring to a landscaper's claim that Terri approached him about a murder-for-hire plot, "so it wouldn't surprise me if she had someone helping her."
When asked about court documents stating that Terri allegedly had been "sexting" a former high school classmate of Kaine's in the past few weeks, Young rolls her eyes.
"I guess to say it tactfully," she told the Today Show, "it goes to someone's character if you're doing something like that. It's disgusting."
Reporting by ELAINE ARADILLAS