When Terri Horman’s 7-year-old stepson, Kyron Horman, vanished six years ago, Kyron’s parents accused her of being somehow involved in their son’s disappearance. Terri was the last known person to see Kyron when she dropped him off at his Oregon elementary school science fair.

Terri, who was never named by law enforcement as a suspect but has remained under a dark cloud of public suspicion, is adamant that she had nothing to do with her stepson’s disappearance.

“I need people to know I did not harm my son,” Terri says, adding that she loves Kyron as her own and misses him greatly. “I’m suffering, too, every day without him … I did not kill him, I did not kidnap him, and I just want him found. I’m an innocent person.”

WATCH: What Was Terri Horman Texting In the Weeks After Stepson Kyron Horman Disappeared?

Terri agreed to take three polygraph exams about the disappearance of Kyron, and she says she failed the first two and walked out of the third. Why does she believe she failed? Watch the video above.

What does Teri think happened to her stepson Kyron? This episode of Dr. Phil airs Thursday. Watch more here.