I wish we knew specifically WHO decides not to prosecute, when the OIG report documents evidence of wrongdoing.
What a waste of tax dollars, to investigate and then do nothing.
Wish we had a name to publicly shame.
The US Attorney in the Disctrict of Columbia, for DC-based FBI agents. Would be US Attorney for other districts, when the activity took place in that district.
This same sort of calculus takes place when a member of the public commits perjury in a federal case, etc., which is very very common. Limited resources, so prosecution is selective. There is enough activity involved that the system is inevitably inconsistent and hypocritical.
There is also the substantial "professional courtesy," where they cut their own peers slack. Same as most any local, county or state police department.