Eighteen-year-old Ebby Steppach vanished on October 25, 2015 and hasn’t been seen or heard from since.

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Her parents say in the weeks leading up to her disappearance, Ebby’s behavior changed “drastically.” They say she would lie about her whereabouts and that she was provoking arguments.

In the video above from after the show, Dr. Phil explains why it’s so important to pay close attention to your child’s behavior, especially if you notice changes.

WATCH: What 18-Year-Old Told Her Brother In Last Conversation Before She Disappeared

“That’s what we as parents are supposed to do; we’re supposed to see around corners for those children,” Dr. Phil says. “You do enough to know what you have to do to protect your child. It’s not an invasion of privacy; it’s a matter of knowing what’s going on so you can provide the foresight your child doesn’t have the ability to do. That’s your job as a parent.”

This episode airs Friday. Watch more here.

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