well its hard to say its one person since the way they were murdered would make you suspect themselves if that makes sense because hoss was murdered by someone who knew the secret passages or it wouldnt be possible and he had at least known one. Orlando was murdered by someone who knew the signifigance of the vault and knew the code to it while Orlando knows neither he is the closest to learning both. Ty was murdered by what seemed like a wild bear/animal and the one who acts the most like one is Ty (no offence I like Ty too). then Sal the poor boy felt immense guilt and Hypnos told him to atone when the only one who he told was you soo... you could also argue Dean since they said they know eachother from before too. while in Deans you were worried about a suicide no more proof then that cause I can't think of any as for Roswell I can't think of anything. after saying this if it's a known character I think it comes down 3 people Dean for the motive, Butler since he suits the bill for a suprising amount of the deaths (these being Roswell, Orlando, Dean and Hoss) and this the most out there one but I can't stop thinking about it you, specifically future you for sal you knew his guilt and nightime hypnotisation for Dean I have feeling we'll figure out were poison is stored soon for Hoss you are learning the hidden passages and future you would know more also you knew he would be knocked out at the time for Orlando butler said we will learn the code to the vault after the medallion chase so future you may know it for Roswell it's another case of hidden rooms since the room was locked in and for Ty I can't quite think of anything. But for the butler, future you knew where a gun was going to be future you may think someone has to die and decided on the poor butler or even thought the butler the killer and stopped him preemptively not sure but I think whitey only appears when butler is missing which is suspicious so it could be the butler so in the end future you may be the killer why I don't know how I don't know but you can see an alternate dimensions future I don't think this that far out there but still it could be
It's probably because these sorts of discussions happen all the time on the Discord server (well not all the time but often enough) that it's always interesting when I see a new take on the how people died and who's behind the murders.
Straight up? A couple of people have already solved some of the murders, but the problem is that despite solving them, it hasn't given them enough information to crack the 'why'.
What I can say is that come Day 10, you'll get some more insight into the details of the murders that have happened so far, so that might help frame your theories a little better.
My advice is to remember that despite Dave's interception of whatever incident caused the murder, or the circumstances leading up to it, other things are still moving unhindered in the background, sometimes regardless of route.