Here’s something I’m interested in. The friends and coworkers that heard the kids inside but couldn’t access obviously would’ve tried both the front door and the back door. That means the door was either in the locked position (your standard bottom knob) or the perpetrator locked the door behind them. In the early pages of this thread, the picture showing their front door shows the keypad. Some styles of those keypads, all you have to do to lock the deadbolt from the outside is press the “lock” button. Meaning you need the code to unlock the door, but not to lock it. If the perpetrator went out the front door and it was locked, it stands to reason that they took this step and would’ve been captured on the ring doorbell, assuming it was functional. I’m highly interested in what type of lock was on the back door. If it was the same, they would’ve had to take the same step to lock it. Was the back door even one you can lock without a key by flipping the knob and pulling it closed? Since there were no signs of forced entry (window open, window screens missing. You typically can’t close a window or return the screen from the exterior) I think we can 99% assume the killer came and went from one of the doors.