You're looking for article 43, section 843 of the United States Code of Military Justice.

a) Subject to section 843 of this title (article 43), no person charged with having committed, while in a status in which he was subject to this chapter, an offense against this chapter, punishable by confinement for five years or more and for which the person cannot be tried in the courts of the United States or of a State, a Territory, or District of Columbia, may be relieved from amenability to trial by court-martial by reason of the termination of that status.

(b) Each person discharged from the armed forces who is later charged with having fraudulently obtained his discharge is, subject to section 843 of this title (article 43), subject to trial by court-martial on that charge and is after apprehension subject to trial by court-martial for all offense under this chapter committed before the fraudulent discharge

(c) No person who has deserted from the armed forces may be relieved form amenability to the jurisdiction of this chapter by virtue of separation from any later period of service.

(d) A member of a reserve component who is subject to this chapter is not, by virtue of the termination of a period of active duty or inactive-duty training, relieved from amenability to the jurisdiction of this chapter for an offense against this chapter committed during such period of active duty or inactive-duty training.