But they should also be accorded a fair investigation and trial, perhaps by a neutral group.

It won't be fair at all. The people lower down the pecking order will be scapegoated, and those higher up the pecking order will not be punished in any way. That's how it's always done.

Personally, I'd rather see the higher ups get punished more severely. They are responsible for creating a culture among the lower ranks that has no regard for human life in the countries they are occupying. That is a war crime of major proportions, and should be punished as such. I think the rank and file are already bearing an unfair burden for things that are the responsibility of those higher up than they.