John claims he’s fought the urge to torture and kill since he was a boy. His younger sister, Jennifer, says that when he was young, John often talked about his “fascination with killing and serial killers.”

WATCH: Author On Friendship With Convicted Serial Killer Arthur Shawcross: ‘He Was Basically My Closest Friend For A While’

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“We had drawings on his table with blood mixed in, and heads chopped off; severed limbs and heads and things sewed back together," she says, adding, “I honestly thought I would find a severed head in the closet.”

Continuing, she says, “There have been so many crazy things that he has done that I’m almost numb to it. I don’t ever want to believe that he could actually follow through and kill anyone, but if one day I found out that John murdered somebody, I definitely wouldn’t be surprised.”

WATCH: Dr. Phil To Guest: ‘You Should Not Be Alone With This Man’

John says he has several “triggers” - including alcohol - that could make him become a monster. But how does Jennifer, who claims she’s never been afraid of her brother, respond when John reveals another one of his “triggers” is her?

WATCH: Today’s Takeaway: Don’t Give ‘Benefit Of The Doubt’ Blindly

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