Employee assaulted by Boss on the job

I am a Projects Specialist for the City. On Wednesday Dec. 17 my boss called me into his office upset over an harassment charge I had filed with Human Resources. He called the incident chicken s##t, then proceeded to yell that he was going to kill me, I got up to leave his office when he grabbed my throat and pushed me into the wall, punched my left temple. I was hit numerous times but after my head hitting the wall I can't recall exactly how things went after that. Police showed up, took the reports etc. The problem is the city police are very friendly with the upper Management and I don't feel I will be treated fairly and am also afraid of retaliation from my boss since he hasn't been arrested. I do not trust lawyers in our city as well, I feel the City has everyone 'in their pocket'