Totally different story of the actual murder, and the "bystander effect" questionable.
My cultural question was about both "Morris was stabbed in the chest... ...the attack appears to have stemmed from a dispute over a girl "and the perception of who she might be dating or who she might be hanging with."" and "at least 60 teens had gathered around the parking lot to watch the confrontation, and some took cellphone video that was posted on social media."
I don't know if Kitty Genovese is proof of bystander effect or not, but based on personal experience I would tend to believe that the bystander effect is real in cases of where the bystander may be harmed by stepping in. Yes, 60 people may be there, but each person individually is risking their life if they respond by themselves.