Although this theory is probably incorrect, I don't think that the murders are connected. I think that each murder was committed by someone different, and none of them are by the same organization or for the same reason. They just all wore a Red Devil costume to conceal themselves. I think that Boone and Gigi are working together, but only on one of the murders. The whole conversation with Gigi on the phone in the latest episode was to confuse us. However unlikely, I think this would be a cool plot twist