DD was not clear at all since he said nothing. That was CDs account, the affidavit was silent on what DD himself said. There was also a second boy there, and again, LE did not say what HE had witnessed. Then later BD provided us with a completely different account of what DD supposedly said.
Instead of using the primary witnesses, who were available, LE instead chose to use hearsay from a third party. Why on earth would they do that? What that tells me is that the hearsay was incriminating, but what the primary witnesses had to say was not. And since they wanted incriminating, they used the hearsay and ignored the primary witnesses. You can conclude therefore that the account given in the affidavit is not accurate.
I don't believe there was any banging. IMO DD encountered a locked door and snuck in. You could speculate why he would do that, and I have provided a reason. Having been a teenaged boy with a slightly younger sister in the past, I can assure you that is exactly what they would have thought if they encountered a locked door when it was unusual. They would have expected to find something illicit or naughty going on, and there is only one person DD would have expected to find there at that time of the day on a work day. Connect the dots. He might have told CD that he banged on the door, as a way of explaining why he broke in, but I doubt that is really what happened.
In the process of entering through the window he caused a disturbance that would have sounded to SA as if someone was breaking into the house. So of course SA would have been very apprehensive when he went to investigate. If there was "banging" on the door, SA would have gone to answer it. Why would he respond to someone entering through a window but not DD banging on the door when in that situation it would have been obvious that it was DD that was breaking in? HD was not in the house so it is not as though he had to hide anything. If there was a cleanup in progress or a dead body in the living room, surely DD and his friend would have noticed? SA was not hiding anything. He left soon afterwards to pick BD up from work, so anything there would still be there since the window of opportunity for SA to have done anything was only about 30 minutes. Not enough time to really even do a crime, let alone get rid of a body and clean everything up. If SA had killed HD, her body would still have been in the house while DD and his friend were alone there after SA left. But they apparently made no mention of anything like that. And SA and BD did some socializing after he picked her up as well, so he clearly was not too concerned about the boys finding anything. That tells me there was nothing for them to find.
The account in the affidavit does not add up. IMO the door SA came in was not the same door DD found locked, so he did not know it was locked. SA probably came in the same door HD went out from, and that one was not locked.
