Because Sgt. Cook had more that just a suspicious person in view. He had RAS that the person looked a whole heck of a lot like the wanted escaped convict.
Because there is almost no support for the welfare and wellbeing of escaped convicts. Especially ones of the wrong hue.
Because the community was so greatly in fear of the escaped convict that they would not have cared how he was taken down so long as they could go back to not being afraid of a specific threat, regardless of that threat having done everything in its power to stay away from the community and its members.
Because if it had happened in Virginia there is a financial incentive to do so.
http://leg1.state.va.us/cgi-bin/legp504.exe?000+cod+19.2-7 Don't know if NY also allows cops to collect rewards.
But most importantly, because the guy refused to turn around so he could be shot in the front.
Have all y'all seen the picture of the cops standing over him like some big game trophy pose?
http://nypost.com/2015/06/28/cops-capture-escaped-killer-david-sweat/ #It'sMoreImportantToGoHomeAtTheEndOfThe Shift