I just wanted to reply to this to explain some things.
You can stab someone and get very little amounts of blood on your person. It's a very possible thing to do and most of the time the problem for the culprit stems from the amount of blood they get on the floor or area around them. That's only if they're trying to hide the body though.
The idea of Rigor Mortis wasn't discovered until the early 19th century. Back then they had very little to go off of when it came to understanding death.
The fact that they were feeling ill doesn't excuse anything either.
Not saying that they're completely and perfectly framed, but trials back then were never fair and a person of his status would most likely face severe punishment.
I'm also not saying that the MC has no way out of this. They can play their cards, but in the end it's all up to the court whether they choose to believe him or not.