hmm, what if Isaac and your room mate that is missing had prior beef? and it turns out David actually had nothing to do with Isaac? and Katie was in on everything? and any money stolen or property that was stolen was actually going to be returned by David?... but he had nothing to do with Isaac... Dont go doing something silly built on initial rage and instinctive behaviour... he has played over every minute right up until this point, he wants a challenge, what if he somehow found out about the previous beef between Isaac and your other room mate and used it? or is it just coincidental. Just because things happened at the same time, doesn't necessarily mean that, who you may suspect, is the actual culprit. But always prepare just in case they turn out to be.... My advice would be and I know its hard to, especially with so much going on around you Zander but gather everything in your head, categorise it, understand every move, learn from the past to predict your future. Good luck mate