The FBI is corrupted. This is so easy. Here is the legal issue. Did she remove the server to her house? EASY!!!! Whay the delay? CORRUPTION!!
There is no excuse, no extenuating circumstances. There is only characterizing the nature-of and quantifying the damage done. There is also looking for guilty associates who aided and abetted. Hillary has to go to prison, has to. Probably several dozen of her staff will too. This is not open for debate. If they do not prosecute and imprison US intelligence is dead. US national security is dead. Failure to prosecute and imprison will be a recruiting boon to foreign agents "Don't worry, if you get caught with a few papers any lawyer can get you off - look, they didn't do anything to Clinton..." and they would be right. Every defense attorney for someone in a national security case from then on would have a get out of jail free card for their client.
Clinton and all her cohorts in crime - including probably former President Clinton - must go to prison.