>What is amazing is that the feds moved forward very aggressively with a criminal probe on David Petraeus. They seem to be proceeding with such a high amount of caution on Hillary Clinton. Major double-standard.

Here is an analogous situation from Wikipedia re: CIA Director John Deutch:

Deutch left the CIA on December 15, 1996[1] and soon after it was revealed that several of his laptop computers contained classified materials designated as unclassified.[clarification needed] In January 1997, the CIA began a formal security investigation of the matter. Senior management at CIA declined to fully pursue the security breach. Over two years after his departure, the matter was referred to the Department of Justice, where Attorney General Janet Reno declined prosecution. She did, however, recommend an investigation to determine whether Deutch should retain his security clearance.[8] President Clinton pardoned Deutch on his last day in office.[9]