It somehow didnt came back to me before, but wait...
Pre 2007 you didnt really need an email to stay in touch with someone online.
It was making things easier, but wasn't really necessary.
I just remembered that my first online contacts were going totally on this one chat platform. I'm almost sure they did NOT require and email to "register" a nick. You were just adding password, and kept logging in with that password but if you forgot it, it was gone. But there was no need to do it, and have like "JaneSmith" nick, you could just write down whatever name and keep coming in as ~JaneSmith or ~JaneSmith1.
It had no chat history, but you were able to leave messages with some code like
#LEAVEMESSAGEFOR#~JohnSmith, and then they were delivered the moment someone entered the chat as "~JohnSmith".
And somehow, it wasnt really a thing for people to log in as other people, even if it was just that not-registered nick. It might be an issue on these big like dating or city, or age group chatrooms where were always hundreds of people BUT in the smaller ones, like "metal music fans" or "Rammstein fans" there were never more than few dozens of people, mostly regulars and everyone kinda knew who's who there.
I cant tell for sure now, but as Im thinking Im "pretty sure" that some forums worked like that either. They either didnt required an email to register, or they werent really like sending any verification message so you could put
[email protected] there, and keep logging with it. And even that only if you felt a need to have your nick without "~", cause posting without a login was also possible.
Same thing as with chats - on the big forums and more popular topic it was just turning into big mess with people signing their troll posts with the ~originalposter nick, but on the more "niche" forums it stayed mostly in order as far as I remember.
So how exactly could LE confidently verify that Andrew wasnt using these ways of communication? The only thing they could possibly tell would be if someone was entering these chats or forums from computer A, B, C and so on, but not if it was or wasnt Andrew.
Unless nobody ever was using forums or chat websites on school, library, friends and sister's computer but how likely is that? That NOBODY ever did?
Maybe with sister's computer they could, cause since she had it for such a short period of time that she and her parents would still remember it pretty well if Andrew was asking to use it or not and how often BUT if there was even theoretical possibility that Andrew was using it in one of his friend's house... then you have parents + kids + kid's friends, so possibly like 6, 7, 8 or even 10 people using it sometimes - then who's gonna remember like a month later who used it and when?
Online communicators werent a thing yet I think but texts on prepaid phone with a code were worth like one day's lunch money.