Right. When I try and figure out how to compare the FBI to british law enforcement I end up with "MI5 smashed together with Special Branch plus SOCA plus a bunch of other specialist bits" ... and I'm pretty sure if we'd done that it'd've been an unmitigated disaster just the same.
It was notable that there was a very brief "scandal" that MI5 had found evidence of child molestation but ignored it because they'd only found it via their ability to ignore due process in the name of national security and therefore since the information wasn't a national security issue it was filed under "not usable".
Cooler heads pointed out repeatedly that that was how it had to work to preserve due process, and it didn't stay news for long; this was, to me, the correct outcome.
(of course GCHQ is a whole different kettle of fish)
And if you read the official history of MI5 the one time an ex police man was put in charge didn't go well - and that's the official history which is going to be circumspect.
The FBI should have been reorganised along with the secret service and BATF after hoover died into two organisations one doing MI5 s role and one as a federal police force.