That didn't actually exist. Two separate excavations never found signs of anything under the school except for a small crawl space someone had dumped some trash into.
The mistake you're making here is assuming that all of the accusations in that report are corroborated. They aren't. Most of it is just a collection of claims made by assorted people, not anything to do with actually investigating those claims.
I'd love to learn more.
> The contents of the “tunnels” further support the likelihood that Stickel had found an old trash pit. Stickel listed many objects that he found (pps. 54, 70, 75). These included sections of boards, wood fragments, a variety of metal objects, an inner tube, numerous bottles, TV antenna wire, tin cans, scissors, eye glasses, exposed film, cinder blocks, plywood, tar paper, roofing nails, four trash-filled pots (three of metal, one of crockery, the largest about fourteen inches tall, all in disrepair), a one-gallon glass food jar, 35 to 40 rusted tin can fragments, a crockery lid, an old medicine bottle, various glass fragments from a large jar, a small “pestle-like stone,” a rusted metal rod, and 60 to 70 rusted metal can fragments.
> More likely, however, is that the alarm switches were placed relatively high on the walls because staff did not want children to set off false fire alarms. The archeologist seems to have considered neither this ordinary reason that fire alarm switches had been placed relatively high on the wall, nor why the switches had been connected to a bell whose location was outside the preschool’s front office door where parents and others entering the building surely would have heard the alarm’s ring.
http://tedgunderson.info/index_htm_files/McMartin%20Scientif...
you will find the exact same pages as included in the finders fbi file. Even if you choose to believe the report, this demonstrates that it didn't actually have anything to do with the finders and in any case was not done for, or by, the fbi or police. it was (presumably) included in the file because it had similar claims to ones made against the finders.
I have read the entire finders fbi file. Repeatedly there are the fbi and police fielding claims that the finders were satanists, or that they were sexually abusing the children, but in every case they document they found no actual evidence of this.
the claim of an fbi cover-up was documented in the fbi file (that would be weird if you think about it) but this claim was made by a single junior member of the manhattan beach police, and is never repeated or corroborated anywhere.
the claim that the finders were tied up in the intelligence community seems to be based on uncorroborated claims as well. nothing in the document or linked resources supports it.
I hope you find this helpful, I had multiple of my friends bring up this fbi release as "proof" that SRA was real all along but after reading every page of the file I just don't think there's anything compelling in there.