Is the only Human to survive the Khitomer massacre, growing up learning the ways of both Klingons and Romulans while living among the disgraced survivors at Carraya IV.
Section 31 somehow figured out he was alive and engineered his escape. In order to avoid servitude to Section 31, he bartered the location with a Uridian in order to go into hiding from Section 31.
Eventually Section 31 caught up with and interrogated him, breaking him and turning him into a one man covert op agent, utilizing Federation, Klingon, and Romulan tactics. Section 31 assigned him to a mission on Romulus, and he went dark for too long.
Section 31 then uses the USS King Edward to have a team take Litwin back dead or alive. Not all of the crew realize they are working for Section 31.
Prior to the extraction Litwin was hit badly in the head causing his programming and past life to all scramble. The XO tried to extract information only the crew caught on and turned on him.
The CMO Major Larson was able to unscramble his brain, and Litwin vowed to help the crew with whatever they needed and to work against section 31 in any possible way.