The problem with modern American policing. It is a lack of for the better term, honor. The police and district attorney collaborate together to put people in jail regardless of the actual mission, which is to determine guilt or innocence. Most police investigators start out as if everyone is guilty and go about proving that someone is such.
They (police, prosecutor) will twist people's words around to fit the pre-conceived guilt. They will manufacture evidence if need be. When the police investigator can not come up with enough evidence to get past a defense lawyer, they end up bitter and disappointed.
Guilt and innocence, convictions and acquittal are tracked like some sort of macabre sports statistical game.