That person dressed as a cop might be completely disconnected from his true self and discharges his frustration on that poor kid. That person dressed as a cop is nothing but a scared little child who lived/lives a tough life, physical or psychological, or both. That cop lacks love and sees on that poor kid an opportunity to release his piled up anger and shoots him. I beleive the source of all violence are fear and lack of love that comes from disconnection from our true selves.