I am convinced there was a kind of big massacre in the village before Edward arrived and after Johan went to confront Fredrick. After all we find out in one house that "the words turned to stones, blood was spilled".

I think it directly refers to that confrontation, at which many people were present, not just Johan and Fredrick, but maybe the complete two factions. I think Johan went through the fence, captured Simon and drowned him, maybe in a well. Then he burned the farm. Although this raises the question: who buried Simon? It was at that point that maybe Fredrick or Fredrick's faction went house by house avenging Simon's death, killing many and writing "Traitor" on many places. Some houses were a mess, the doors, though, were not broken, they were not even closed with the key, this makes no sense... The faction that won must have buried the corpses in the church graveyard, destroyed the church and filling the book of deaths (?) and then fled the hopeless island... or committed suicide. What do you think? This theory leaves out the arsenic factor.

We also have to count the destruction of the store. It was of course of Johan's faction's doing, but there is one thing that doesn't make sense: why the blood writing "Traitors" on the wall? Wasn't that the word Fredrick used to describe his enemies? Maybe Johan wrote it to mirror the accusation of his enemy: he is the real traitor...?