Even before speaking with police though, it is quite likely that the girls who saw someone on the trail that day conferred with eachother, and possibly their parents and others BEFORE they contacted LE. So according to the research I've done on the issue of witness reliability and accuracy, it seems that just the act of discussing what they saw with eachother could easily have impacted their statements to police. EG:
If the kid were walking and noticed BG, one may have said to the others at the time something like (and this is ONLY an example, so do NOT take as fact pls):
1. Omg did you see that guy! He just STARED at me!
2. What was with the face covering?
3. And why the need for a hat? Wait, are you sure he was wearing a Face covering?
1. Right? That covering just made those eyes creepier!! I saw a hat, it was brown.
3. No it was green!
1. Oh! It must have been green, you're right!
So now they've discussed it and formed their thoughts collectively and then the murders happen and now they're really talking to one another and parents and others (likely) about it before calling LE. And now somehow someone thinks he had blue eyes, someone else thinks brown. Someone thinks he didn't have a hat, but someone thinks he did - that person doesn't want to seem unreliable so they just agree that he did.
Then they talk to police... if police say:
Your friend thinks the guy wore a green hat is that right?
The witness, who wants to be helpful, might just agree with this because its been suggested to them. By the cop, by the friends etc... even if they aren't 100% sure of the fact themselves.
Ideally, a witness sees an event and does not talk to anyone before writing down what they saw and giving an interview to police to get it recorded. I'm not saying this happened here, but I'd really like to know what the events were that lead to the kids calling LE to report what they'd seen - who they talked to, when, how long before they gave statements etc. How similar were their statements? Where did they differ?
It is just an interesting topic to me considering that witness statements are a major factor in wrongful imprisonment.... imo.