we're following a disturbing story out of arizona. this man here fatally stabbed a 17-year-old boy at a convenience store cutting the teen's throat, because he claimed the rap music the boy was playing made him feel unsafe. witnesses say 27-year-old michael paul adams walked up behind the teen and stabbed him in the neck. those witnesses also told police the victim did nothing. nothing to provoke the attack. ryan young is covering this for us today. why? how? >> still tough for this family. sad, sickening, really just unreal. a 17-year-old killed in a gruesome way for no reason at all. he walked inside the store,