Hi @JNark Best of luck on your investigations, it would be great to bring some closure to his family instead of leaving him as a nameless John Doe. Not sure what @MrFaul is ranting about dangerous knowledge, please don't take him as representative of the community here.
However, I have to inform you that the "Ben2" that MrFaul is talking about is very unlikely your victim, as his steam profile shows he unlocked a number of badges in the last year. https://steamcommunity.com/profiles/76561198004426967/badges/ This makes it very likely that that user has had activity recently (the last one unlocked, "power player", was 3 days ago and I think it represents owning 100+ games).
The notes are most certainly screeps related though. Let me know if there is anything else we can do to help. I should call out that these are the new forums here. IIRC there was some old screeps forums that had content prior to 2017 that could potentially have information, but I'm unsure as to what happened to them.