I Am a Killer

Overkill (2x5)

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In 1996, David Barnett murdered his adoptive grandparents, stabbing them over 20 times with five different knives. His motivation for doing so remained a mystery until it was discovered that David Barnett claimed to have been subjected to years of physical and sexual abuse, not by his grandparents but by their son, his adoptive father, John Barnett.