They have the right for trial, you can't juat do that. There are laws for a reason
In today’s time in most developed countries, yeah you have rights.
I doubt the world they’re set in has such rights. Given how they rule by hereditary nobility, a clear class system involving slavery in some countries, also there’s magic powers, and I’d hardly call it a developed world….
I’d agree if this was the real world, but with their sins (killing 100’s of thousands to millions, plus all their other crimes), not to mention they also have powers/they’re sneaky snakes so there’s a high probability of them being able to escape the safest thing would be to quickly execute them, make sure the “holy kingdom” remnants aren’t attacking, and then round up the corrupt nobles.
Ugh, skip the trial just send them straight to the chopping block and publicly announce their sins (╯°Д °)╯╧╧