In my little town, way back when, police used to rough up prisoners routinely. One thief had the misfortune of stealing the purse belonging to the mayor's wife. When he was arrested, the police beat the living daylights out of him. The suspect was held in the local lockup overnight until the county sheriff sent a deputy to transport him to the county jail. When the deputy saw the guy, all bruised and boodied, he asked what happened. The police replied, "he fell down a flight of stairs." The deputy didn't believe the story, so he asked the prisoner. "Yeah, I fell down some steps," the suspect said. I suppose he and/or his loved ones had been threatened if he told what really happened.
This went on for years until one guy, who had been arrested but was later cleared of a crime, filed suit against the police department and won big time. It took a hefty payout to cure the police of such behavior.
No, Trump, it's not a good idea for the police to beat up a prisoner. And you, the supposedly well educated guy, should have known that.