1) The wording seems excessively modern for the typical D&D setting. Words like "pathogen" for example. I suggest changing "via pathogenic weapon" to "via an infectious disease" and changing "genocide" to "eradication of a sentient species". Furthermore, I'm not sure that they'd bother to make any distinction between murder in the 1st degree and murder in the 2nd or manslaughter, nor with murder "with aggravating circumstances". I'm not even sure what that last one means. The idea of "war crimes" also seems too modern, or at least the things that we consider to be war crimes today was just war in olden times.

Of course, this is all highly dependant on setting. If your setting has a much more modern criminal and legal system (or if the setting is more modern in general), then the wording could be left as is.

2) Well, I think the one convicted of attempted genocide and mass murder using illegal magic sounds by far the worst, although the mind control/war crimes guy sounds pretty bad, too. The first guy just sounds like an enemy of the government, what with all the treason.

3) Well, it seems like the first guy hates the government. Not necessarily government in general, but specifically this government. High Treason means treason against the king or ruler directly, right? So maybe his goal is just to assassinate the king. It seems he's gotten quite the incedental body count.

The second guy seems like your typical Dark Lord evil magic user, spreading magical diseases and using curses and hexes to kill people. Probably did some magical experimentation on his helpless victims, too. And he maybe tried to summon Cthulhu. Traditional pure evil.

The third guy seems more chaotic, or else he's just a mastermind type who's true goal isn't really revealed by his crimes. He used a lot of mind control, formed his own army and sent it against the government or was involved in some kind of coup. He also used biological warfare, and did some other horrible things depending on the exact definition of "war crimes". He's more or less entirely despicable.