I doubt the FBI are doing much.
Apparently, there's insufficient evidence to charge anyone. Had Epstien not experienced his untimely death then, presumably, that could have changed.
There's also Maxwell, who is angling for clemency from Trump, who has been afforded remarkable privileges in recent times by the Justice Department - particularly being moved to a much nicer and low security prison (which, of course, happened very shortly after it became clear Trump's own party would back the release of the files - causing an extraordinary long recess - and Trump's former personal attorney, paid her a visit).
It's odd, isn't it, that the Administration does not appear to be suggesting the possibility of clemency if Maxwell offers enough useful information or evidence to secure some convictions? Instead the Administration seems quite keen to obstruct the release of the files and remains desperate for everyone to shut up about them and move on.
Thank goodness the current administration isn't also exerting unprecedented influence, in ways that upend constitutional norms, over the Justice Department based upon the whims of sitting president....otherwise, it'd almost look suspicious.