Would the deceaseds’ cars be left at the scene of the crime? I initially thought they’d be towed to police headquarters but if they don’t feel any part of the crime took place in the cars, then maybe not. Still in that situation, would families of the deceased take the cars away and back home? Or maybe LE told them they had to stay at the house in case they needed them later? Still in that case, wouldn’t they want them in police custody so they could make sure no one tampered with them? Is it possible the car being searched was one of the surviving roommates’ for some reason? (Not suggesting they are a suspect at all. There could be other reasons for searching them).