What comes to mind is the old saying:
The first sign a person being knowledgeable is knowing what they don't know.
We know what we know from L.E. and Arrests and Indictments ETC.
However, thinking that is all inclusive is the mistake.
If they never were arrested they never existed.
As I mentioned I haven't been around this for years in Brooklyn and a few years back I knew of at least 1/2 dozen guys that were made that never showed up on any lists or their arrest records weren't all over the internet.
The point I am making I am not up to date because i am not actively involved.
So if I know of 6 how many are there?
Historically?
Today?
To put it nicely the FBI knows Jack shit when it comes to the Outfit.