I'm gonna say yes - not killing them in cold blood execution style but in the sense of them being a valid target. If you're in a position to torture/rape someone, you've already neutralized them as a threat by capturing them. Shooting or bombing someone is not necessarily OK, but while the person is at liberty they could in theory be about to shoot your or engineer some other sort of attack - the operation to assassinate Admiral Yamamoto in WW2 being a good example: http://en.wikipedia.org/wiki/Operation_Vengeance

On the other hand, torture isn't something that people do because they feel they have to, but rather because they can. Since all the accumulated evidence to points to it being a poor way to to gather intelligence information, it's hard to avoid the conclusion that it's just way of being vindictive or sadistic instead, something that we find deplorable in other contexts. I think it's considered deplorable because such feelings are quite common but the majority of us make the effort not to act upon them.

>But killing them is ok?

the human race so far narrowed it down to 2 possibilities - judicial proceedings or war following the rules of Geneva Conventions. Every other form of violence is a crime, with torture and killings being the crimes against humanity, prosecutable by any government and without statute of limitations.

These torture victims weren't even allowed to kill themselves. At least one tried to gnaw through his own veins just to end it all. Yes, this kind of torture is worse than murder. To the victim, but also for the perpetrator, because it's done in cold blood for a prolonged time. You have to have a truly sick mind to be able to do this and continue doing this. The people doing this do not belong out on the street, and they certainly should not be holding any kind of authority.