Small houses can be strangely big seeming inside, if the rooms are placed particularly, you can’t always hear what’s going on through the whole house, especially garage/outside movement.
Personally, I seem to always have my deep sleep cycle when the two other people in my house get ready and leave for work. In fact, they’re pretty loud people and I rarely seem to wake up (thank god) and my room is off the kitchen/bathroom (loud rooms). I wouldn’t even consider myself a generally heavy sleeper, either.
Given the fact they had to scour the house/living room for any traces and clues, I’m assuming that the fatality would have been swift (strangulation?) as opposed to a loud argument/fight/altercation that would have left more evidence...
