Caramandi and Scarfo were already on bad terms before the crow got arrested. I really do think Scarfo would have killed Caramandi especially after the crow had told Nick that he would not interfere with Scarfo's kid from seeing Caramandi's stepdaughter.

"I have this Nightmare. I'm on 5th avenue watching the St. Patrick's Day parade and I have a coronary and nine thousand cops march happily over my body." Chief Sidney Green