Someone, or something; probably not in the apartment, but perhaps nearby; perhaps with access to the ventilation system. The details are unknowable and therefore do not matter near as much as getting out of here. Anders has already donned his coat and shouldered his messenger bag. "Where? Anywhere public. Just for a couple of hours, until your place airs out. Leave the harness on the dog, we'll say he is a service animal in training so he can come with us. Or, hell, we can just sit in the car. My car or yours? Better be yours, someone's been into mine already, to leave that earring."