In regards to the search and the perp joining in...I am wondering at what point they would have interjected themselves. If memory serves me correctly, during those first hours it's possible that only LE, first responders, and family were the only people involved in the search. Unless the family had called around to friends of Elizabeth's to see if the girls were at their home (and actually requested assistance in physically searching) who all would have known to go look?
Did someone just happen to show up at the park wondering what all the fuss was about? From reading MSM it sounded like it was really just Lyric's family and LE at Meyer's Lake - I don't remember mention of Heather or Drew being there. I may be wrong, but for some reason I have a memory that Heather didn't participate in the searches, but stayed back in case they came home (which makes sense in case they finally showed up).
I just don't remember seeing the masses of help come in to search until later on that evening and then the following days. I remember an article about people saying they had seen people in the park with flashlights looking around in the woods, and we know Tammy mentioned the family did their own search of the wooded area until LE finally put up the crime scene tape and got everyone out of there.
I just wonder if anyone other than family was even aware that real searches were underway until several hours after they were long gone. And if those people were aware, were they also searching in areas that (in hind sight) should have been taped off immediately? If someone else's DNA shows up in the taped off area, it's possible they would have a valid explanation as to why it's there...they helped in the search.
The question being - Should that person have even known about the search?
I know of one person who searched over the weekend but not on that Friday. I remember there being a short story about it on the 5:00 and 6:00 p.m. news but nothing real extensive until later that night and no requests for people to help search until at least Saturday. We don't have weekend noon news in this area so if anything was mentioned it would have been on the evening news or online.