Unfortunately; Abby was deceased when her body was discovered. She wasn't able to tell them anything.
I would agree with you in the literal sense that she was unable to tell her tale, but with a body found so soon after the crime the whole story is there, it just needs to be read and the tale told. That is what is so frustrating about this crime, there is a full story here.
Method, motive, signatures. We even have a sound track and visuals. What more could be wished for?
If a sex worker goes missing from near a trailer park, found months later in a ditch in the next state - that's a murder with nothing to go on and yet they do still get solved.
But the Delphi killings have all the boxes filled. All except the one that gives his name and address, and LE want that delivered into their laps too, the 'one key tip'. As someone said before me, EVERY crime would be solved with that 'one key tip' because it's the one that gives the answer.
I admire Supt Carter and Mike Patty's religious beliefs and their assertion that 'good will always win out over evil' (Down the Hill Episode 9- 31 min), and that they hope it will be resolved 'in our lifetime', but most of us run to a shorter timescale, and meanwhile this killer is still out there undoubtedly taking more innocent lives.
I'm sorry and I know everyone involved in this case is desperate to solve it but something major has to have been overlooked; and with no progress an element of complacency has crept in. Without a new set of eyes, be that a new task force or public information I cant see this case going anywhere any time soon.
Another couple of attacks may do it but given this killers vile MO "How you left those girls is not how they are today" I don't find that reassuring and nor would any poor potential victims.