You are going to need a good lawyer, and some good evidence. Cases like these arent easy...especially when your word (or the word of any ONE person involved) is never going to match up to the word of TWO cops who are both sworn in.
I have a friend who was beaten by two off duty cops because he took a picture of their boat and license plate as they were leaving a lake with eurasian water milfoil after not washing their boat as he requested them to.
Not all cops are bad guys, but there are bad nuts in every tree. It is sad though if what you are saying is true that this sort of thing has to go on in the world.
Granted, it also sounds as if your uncles are growing more green than they know what to do with.