How does one interrogate a suspect that has so much power? If the local constables suspect an archmage of murder, what exactly can they do? A powerful wizard can pretty much use magic to hide his crimes, or resist any attempt of honest questioning.

I suppose the authorities can find a stronger wizard, but what happens if it’s the strongest wizard in the realm that is accused of wrong doing?

Do evil wizards automatically get away with murder in a fantasy setting as long as they’re the most powerful wizard around? Guess that’s one explanation for evil wizards trying to acquire more power…