I like this idea, actually, maybe with it being a few agents, as Ana suggests, investigating a cartel and then discovering the Deck. I know Elisha and Ben (though he's now an NPC) both have ties to Interpol, for instance, so it could even be someone going "just where the hell did [x person] go?" and investigating long enough to stumble in. That's actually how Abby found it, so it's definitely possible.