But I don't think it's the same as cold-blooded murder. US servicemen are all paid for their service. Most military contractors (and when I say most, think 98+%) are former servicemen that want to do what they were doing while in the service, but get paid a bit more while doing it. I don't think that makes them mercenaries. They are still generally motivated by the same love of country.

The ones you need to look out for are the ones that keep a head-count. Those are the ones that are pretty messed up in the head and go on a killing spree when they get home. They are murderers, but they are also pretty messed up. I still wouldn't put them in the same category as a first-degree murderer, personally.