If a commissioned officer in the National Guard commits an offense against the Uniform Code of Military Justice and gets out (not retire) of the military fearing their command finding out, but still maintains privileges of an ID etc… Can they be brought back to be held accountable? Can the officer lose any of their privileges?

Yes
(from an officer in the Navy)

First an officer does not get out and keep any priviages ( unless retired), if they still have an active ID ( not one they just refused to give back) then they are in some level of reserve status.

But if a crime is committed while on duty and they get out completely, since the crime was committted while on duty they can be returned to stand charges for the crime even though they are completely out ( discharged)

http://www.au.af.mil/au/awc/awcgate/ucmj.htm

Welcome to the forum. The above site is the major site for all military justice issues, no matter what branch. Hope you find what you're looking for here.

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Usually after leaving the military, some individuals have up to 90 days ID priv's to take care of last minute issues, but then should have to turn them in.