Power corrupts.
A badge, a gun, and the right to shoot you dead?
Turns otherwise normal humans into vile, vituperative crease-wipe swine. Lesser forms of this same sad truth are seen anywhere and everywhere people are given power over others.
Having said that, there will always be individuals who color outside the lines of their authority. There sometimes is a fine line between the criminal and those willing to get down in the gutter with them and be a cop. But be careful not to paint all law enforcement with the same brush as those individuals who misuse their power. For every bad cop, there are hundreds out there who do their job properly and according to the rules. Just remember, the people they have to deal with are usually the evil, lowlife, scumbag cretins of society, so their jobs can't be easy.
This guy who claims to have been beaten up, fled from police and scuffled with two cops. Not a wise thing to do if you don't want to be treated a little roughly when caught. You've already made it clear to the cops that you are not willing to cooperate with them. He probably got what he deserved.