[contentcards url=”https://nypost.com/2024/12/05/us-news/grinning-suspect-who-killed-unitedhealthcare-ceo-brian-thompson-police-seen-in-newly-released-pics/” target=”_blank”] By Joe Marino, Georgett Roberts, Ronny Reyes and Matt Troutman A chilling photo shows a suspected gunman grinning widely while supposedly “flirting” with…