This really is pretty messed up.
They pick up a guy, isolate him, and beat him. Then they say "okay, we'll stop beating you if you say we never beat you."
This is the U.S. government we're talking about.
This is part of the reason I've never understood why we tolerate plea bargains. Don't they encourage people to make false confessions out of fear of what will happen if they don't say what the government wants? The only convincing argument I've heard in their favor is that, whether we officially sanction them or not, they'll happen -- so we might as well make it official so we can keep an eye on them.