When Simon is getting attacked by the flies they preferred the dead pigs gut which had turned black do to the flies. Simon gos up the mountain up then sees the dead person. he put the parachute in the air  so that it moved. They decided to go to keep an eye on everybody. piggy gets burned by the boy with the meat and starts dancing and every body thought it was funny. that the counch dose not work in his tribe but then Ralph tells him that it works on any part of the island.The whether starts to be bad like there was thunder and it started to rain.
They say cut his throat spill his blood bash him in. Simon comes out and then they think it was the beastie so they kill him.
I think that evil itself was the death of Simon. In the book the lord of the flies says that if Simon trys to tell the rest of the boys the truth about the beast that the other boys would kill him and they did but i think that evil was controlling them. another reason why i think that evil killed Simon is because even Ralph and piggy turned evil.