This is debatable. Although DJ claimed to supposedly have full access to the case files, someone on an earlier thread claimed DJ only had access to a few records (not sure how they knew that, since LE is supposedly so tightlipped). So, maybe he did, maybe he didn't.
Sorry, I haven't made it clear enough that it's just my opinion that he had that access.
He was working with case files in Fort Worth (not this specific case files, case files in general) for God knows how many years and in what extent.
During that time local LE likely had no reason to connect him to this case, cause he had no official ties to it, and probably he wasn't doing any freelance PI jobs apart from what he had to work as a defendant's office official "PI".
So they had no reason to be on guard, he could be doing some
archivist's tasks or using an excuse that he's checking if everything is archived right and getting access to this case files while doing it.
I can't imagine him being unable to do that if:
a) he wanted to get it,
b) he was kinda working there as well.
And I can't find any reason for some random guy (who wasn't a cop or investigator, nor even a PI hired by family)
to get access to some of the case files officially. Cause why? Why? If he could get it just like that, then either anyone or hundreds, possibly thousands guys doing kinda-official kinda-investigating job could get access to it. Was FW police dep. allowing any random loon to look through some of their case files?
Also while reading random articles and trying to figure out what his PI job at the def.'s office was I kept stumbling on mentions that those guys are much more effective in their work than independent PI's.
Just my conspiracy theory, but sounds to me like they have, on average, much better access to case files and much better communication with cops by default.
I'm beginning to wonder about that...
Oh, and also this.
This is part of the article from '75.
I have no idea how I managed to miss it and overlook the fact that guy is ensuring the public that girls are runaways and that they all authored the note that ended up delivered to TT.
Not LE, highly praised Swaim was doing that, months after their disappearance.
Like it wasn't enough that only tip line ended up to be publicly in press as A's house instead of cops.
And I can give FA a pass with that. It was 1974, she may not know any better and do that with all the best intentions, to get as much info as possible.
But one thing, or even two things there.
First - she may be righit, cause it looks like at least one highly suspicious tip provided to LE was ignored for over 25 years and not followed at all by cops (I mean the one from Sears security chief).
Second - it seems like
coincidentally all important calls with info about the girls were made to A's home. That opens up a possibility that they were faking some of those - maybe not, but still, for the investigation's sake it'd be better if cops were getting it straight. Or it wouldn't, if what LE got wasn't investigated at all.
And the end of the article:

So this "Dirty Harry" insider, just months after the disappearance was only interested in surrendering only directly to the district attorney's office... wouldn't it be sort of where DJ was
professionally hanging out?
That's what really disturbs me about this case. Nothing about it is workable. There's very little consistency. Virtually no one's statements agree. Did everybody have something to hide?
It can't be just that. People are people, almost everyone has "something" to hide. Lies, changing stories, vague or inconsistent alibis, failing memory, wrong recollections, less confident people ending up convinced that they saw what the more confident whitness is saying that they saw - cases without that or with very little of that are getting solved quickly. There is nothing unusual about it. More people connected to the case, more interviewed, more mess follows.
But that's investigators job to make sense out of it. And they do, on the daily basis.
Here it looks like those who were supposed to make sense out of it set their goal on trying to show the least sense it could possibly make.