Karlie Gusé vanished from her home in rural Mono County, California in the early morning hours of October 13, 2018. Her father, Zac, says the last time he saw Karlie was around 3:30 a.m., and her stepmother, Melissa, says she last saw Karlie at 5:48 a.m.

TELL DR. PHIL YOUR STORY: At your final breaking point?

The couple says they believe someone may have taken her. They say they have hope that Karlie is alive somewhere – and adamantly deny having anything to do with the teenager’s disappearance.

WATCH Dad And Stepmom Adamantly Deny Involvement In Teen’s Disappearance

Karlie’s mother, Lindsay, says she doesn’t believe them. She says she thinks her daughter may be dead and claims that Zac and Melissa know more about Karlie’s disappearance than they’re admitting.

“I think everyone should put their personal agendas aside and focus on one thing – and that’s to find Karlie,” says Dr. Phil in part one of this two-part episode airing Monday.

Watch the video above for a preview Tuesday’s conclusion, then check here to find out where to tune in.

If you have any information about the disappearance of Karlie Gusé, please call the Mono County Sheriff at 760-932-7549. Choose option #7. 

TELL DR. PHIL YOUR STORY: Have a story in the news?

Stepmom Of Missing Teen Claims She Was Acting ‘Very Strange’ In The Hours Before She Vanished