I don't think that's quite the point childofares is making. And it doesn't matter who believes they're guilty, other than the jury. That's why investigators want to get offenders to admit their guilt; because it makes convictions much easier to obtain in court. Investigators try hard to get confessions because it's part of their job.

I think what childofares was getting at was that threats made in interrogation are just threats. Threatening people with violence is, of course, itself a crime, and I can't condone that; but applying psychological pressure of various sorts is pretty much the only legal tool that can be applied when interviewing a suspect, other than asking them nicely to confess.