Original sentence: Canadian police have admitted one "protester" with a rock and a bandanna tied around his face was in fact a police officer.The Canadian police insist he was there to stop any violence with his rock.The video shows a burly guy with a crew cut handling a hefty rock and trying to throw it at police while real protesters try and stop him.Video has identified police officers, in one case by their SWAT issued police boots, at several protests acting in this capacity