Being told to confess (confess! confess!) sounds downright medieval. [Redacted some stuff comparing American police to police in some other countries, accusing them of being especially aggressive.] I don't know why anybody would accept being treated like that, without being told what they're being accused of. I would complain in his shoes.
Keep in mind that, in the U.S., the benchmark for bad treatment by police is being shot while complying as fully as possible with their instructions (for which the involved officers are virtually never punished).
