Six years ago, Kyron Horman disappeared without a trace. His stepmother, Terri, the last known person to see him, says she took him to school and watched him walk into his classroom before he vanished, never to be seen again.

In the video above, Terri describes the morning she dropped the 7-year-old off at school.

WATCH: Terri Horman On Disappearance of Stepson Kyron Horman: ‘I Did Not Kill Him’

“The last thing I remember is the back of his head,” she says.

Kyron’s mother and father claim that Terri knows what happened to their son. Terri has never been named by law enforcement as a supect in Kyron’s disappearance, but for years, she has remained under a dark cloud of public suspicion.

WATCH: Was Stepmom of Missing Kyron Horman Involved In Murder-For-Hire Plot?

Terri, who says she loved Kyron like her own child and would never hurt him, speaks with Dr. Phil on Wednesday to “set the record straight.” And on Thursday, Terri answers questions about what some have alleged was suspicious behavior in the days and weeks following Kyron’s disappearance. Check here to see where you can watch.