<snipped and bolded>
The time frame has always been a part of the crime that I haven't always agreed with others on.
We know from numerous (public) LE interviews that investigators believe the girls were murdered shortly after the recording "Guys- down the hill". What we don't know is what time the recording took place. We can speculate, but there has never been confirmation- this is one of the things LE has kept to themselves. It may play a large role in the case.
Another fascinating fact is that DC has remarked that the murder took place where the girls were found. They were not removed from the crime scene and brought back. They lost their lives right where they were found.
I have no doubt whatsoever that BG was still present when DG arrived to pick the girls up. BG picked the location very carefully; which leads me to believe he was very familiar with the layout of the trails, the location of homes, and at least the bottom half of RL's property. He knew no one could see or hear the girls, or anything that might be occurring from the time of the abduction to the end of their lives.
Let's say for a moment I am correct about BG still being on-site at the time of Derrick's arrival. Let's say that additional family members did not begin arriving until closer to 4pm. We know that family members (and searchers) focused on the trails near the bridge, as well as the areas near the creek. IMO, BG knew searchers would focus closer to the drop-off (the Snap Chat photo with Libby on the bridge was not discovered until much later in the evening). BG also knew the location of the crime scene was isolated and difficult to get to. He probably knew searchers would need permission to search on private property. All of these things could potentially extend the timeframe by a couple of hours- leaving him plenty of time to complete his "task", spend time at the crime scene (after the murders), and escape the area. Because of the number of searchers present on the evening of the 13th, the early sunset, and the use of flashlights due to the darkness, I believe it is entirely possible BG may have blended right in without notice. I don't necessarily believe he participated in the search, but I believe he could have used the opportunity to disappear much, much later than any of us has imagined.