I think Brady and the like get locked up in Broadmoor which is a classed as a hospital, though I believe Brady has always tried to maintain he's not insane, which he clearly is.
Regarding Doc's point, killing someone, whether its 'lawful' or otherwise will always sit uncomfortably with me. It's a poor reflection of a society that resolves it's problems in this way.
Self defence I understand, otherwise it's murder in my eyes. Particularly the inhuman way state murder is often conducted. And that's pretty much how I stand on that particular issue.