I was once told by Scipio a while back that Shelia attended a party that evening before the morning of the murders. Assuming this is correct had she remained out and not planned to returned until sun rise, Jeremy would be in a very awkward situation where by he has killed everyone but cant find the person he plans of framing lol
That would have been a severe case of 'don't you just hate it when that happens'

. However, the party was on the Saturday before and she didn't go anywhere the evening/night before.