One of those things is the likelyhood of drugs. But there are also people linking the 3, previous events including previous partying, including Person X. Seems more than likely that Soap Opera-ish elements driven by opportunistic circumstances ranging to a devious manaipulative mastermind are also possible.
The bottom line is that this smells an awful lot more like an inside job than anything else. We just arent' sure, which insider(s) made which play.
By deduction we arrive at less and less possibilities which create new questions to further be ruled out. I want very much to have most of my questions and ideas ruled out, because that begins to reveal the truth.