Anything is possible but how would it happen that in a single video recording, man #1 is seen walking on a very long bridge, towards the girls and then man #2 comes from the other direction, telling the girls to go down the hill, just at the same time man #1 would have reached them and be totally innocent? Man #1 would have had to turn around, apparently not notice anything happening with the girls.
Theres a few ways it couldve happened ,
IF "BG" isnt involved, (and for the record I believe he probably is).
First Ill state that too much weight is put on the composites , and certain aspects of the video especially in this case, remember they changed it completely , once already, its from a very grainy poor quality video for only a few seconds
Early on they also remarked on the way he walked, till it was pointed out he was walking on railroad ties over a very high bridge, so that went away.
ALso I see a lot of people talking about his body type etc.. Ive recall a suspect once losing 40 lbs in just under a month , ive seen guys gain weight just as fast, the suspects height etc.. should be listed as "possible at best" so its important not to rule out a suspect because of how he looks at the time of arrest just an FYI for this discussion (not you personally)
So was BG involved ? ..Maybe, my feeling is probably, but if you want to be an investigator, you have to consider the possibility he wasn't either.
Perhaps the offender is in that area (by chance or by design) maybe he just waits till the BG walks by then makes contact with the victims, that may be the reason he had to move them "down the hill" because there was someone around .
If they weren't , why not just assault them where they were, theres a reason he had them go out of sight, he knew there was too much risk on the trail with 2 victims, but was that because he knew there were people around?
Again that cant be sliminated as a possibility.
SO if he wasnt the guy who killed thr girls , why wouldn't BG come forward? its not all that uncommon actually, and there may be a few reasons, 1) Paranoia, theres a video of him walking in an area where 2 girls were murdered, and hes considered THE suspect, perhaps he has legal issues of his own , or other legal reasons... Sounds weird, but it does happen. 2) Maybe he saw something but is afraid to come forward for his own safety 3) Maybe he doesn't care, 4) Maybe he has no clue the girls were there . 5) or maybe he was part of it , but wasn't expecting there to be a murder (IE more than 1 offender)
How the offender garnered their cooperation is up in the air, and depends on victimology, he may have produced a weapon and forced them to walk. He may have just threatened them verbally, He may have produced, credentials such as a badge and ordered them to walk, or he used some type of ruse or con to get them to comply.
Whats tough to ignore is the fact they videoed this individual walking toward them and then recorded a voice, tells me they were alarmed at some point .
I think when he (Or they) gets them where he feels safe , he acts out incapacitating one victim quickly then the other (sexual assault is never indicated) but given the statistics, it would be a safe bet.
In order to analyze a crime, you have to look at all angles, and let the evidence keep you on track.
Again I will say I believe that the individual seen walking toward the girls was indeed involved, but until an arrest is made its all speculative .