Well i played a few other routes and the patreon version.... so
[SPOILER]
I turns out the MASTER was indeed Roswell and he was behind the murder on day 6 and Benson. Benson let Roswell kill him to save his friends. Pretty obvious in hinsight as Benson is an assasine who cannot be killed by a bunch of halfgrownups except he allowed any of them to murder him. Route A; Also the group agreed to send Dean into the woods (with Oswin) instead of Dave or Roswell. So aside from the sus vision with Dave and Dean (who is holding a gun) in the woods, there is no more evidence towards my traitor theory. Even more disproven; Dean always dies if you fail the password on day 10...