--employed trained professional Investigators.---
Ain't that the truth, nothing but the truth, but not the whole truth.
In all too many cases the "trained investigators" were defrocked state police, relieved of their state police jobs as the results of everything from Internal Affairs/PIC type inquiries, to Royal Commissions.
Apparently such "credits" on a CV were not impediments to employment with CASA or its predecessors. Indeed, the main qualification seemed to be a belief that "Guilty until proven innocent" was the preferred legal doctrine.
After all, a previous head of whatever the legal branch was called at the time stated (before plenty of witnesses --- meeting the criminal standard of proof --- beyond a reasonable doubt) that:
"Pilots and engineers are just criminals who haven't been caught yet".
Sadly, the aviation law in Australia, does, and has done for many many years, create "Inadvertent criminals".**
It is a very old problem in Australian aviation.
Tootle pip!!
** Page 59, Air Safety Regulation Review, first report, The Legal Framework of Air Safety Regulation, 05 December 1988.