I was thinking maybe she put him in a suitcase almost immediately, if for no other reason than to be able to move him quickly. And maybe the quickest and closest spot to hide him was the utility room, since moving a car into the garage and whatnot wouldn't take priority over cleaning up the scene. I thought I read in the AA there was trace evidence from the utility room to the garage, so I assumed the path was his room to utility room for a bit, then out to garage. MOO
RDs video would have caught the time she backed up the Tiguan if any back light.