I'd recommend you talking this over with your lawyer. The initial consultation is usually free and the lawer will advise you what his opinions and what the likely outcomes are. My guess is, you can sue for 2 things -- the return of a month's worth of rent, and secondly for bodily harm and emotional injuries. The lawyer will likely send your landlord a letter warning him of the consequences if he doesn't provide you with the month's worth of rent. I dunno if that lawyer letter has the power to ask him to reimburse you for your bodily injuries though. Then again, the letter alone would likely cost upwards of $400, and should you decide to process to the full legal process, it will cost a lot more. But should you decide that vindication is more important than money, then you should go ahead with the legal process route.
It would help tremendously if you have actually signed a rental contract with your landlord. And the cop is likely suggesting you to let the bastard go because he knows of the financial costs that would be involved.
Unfortunately, a lot of times seeking justice is a rich man's game... 
-Lik |