I don't think police really care what happens after the arrest most of the time, unless it was someone they feel wronged them. I could be wrong.

Point being, letting the guy get off, the police will just blame the lawyers and not themselves a lot of the time.

You always hear, "they got off on a technicality," which means the police were sloppy and didn't do their job the right (constitutional) way, but it infers someone did something wrong in the courtroom and not the police.