Surely a genius like Moriarty has a squirrel disguise where he hides in the park to spy on people. 

I never got into supernatural but my friend was WAY into it. And I'm sure the crazy guy would need to make his experiments appear as though they worked since, if they didn't, he's likely to get killed since "no loose ends" and all. I think this could divulge into other areas of deception, with it depending on what traits we'd need to emulate. But it sounds like we've got that settled.

Should we assume missing people and animals have been...er missing for like a month? But there's no pattern (since he needs new subjects at random?) no one really cares? In this case, maybe Mary's child she's teaching as a governess has vanished, and so has his dog, a few days earlier? Would that work?

And it's on TBS for me, if that helps.