Agent for the Shadows aboard Earth Alliance station Babylon 5, where he served from 2258 to 2261. In his former life, an officer aboard the Icarus on an expedition to Z'ha'dum. (To this end, was briefly held for questioning by Captain John Sheridan in 2259.) Returned to Z'ha'dum to negotiate with Sheridan in late 2260. In 2261 fled to Centauri Prime to form a Shadow colony, but was killed by Londo Mollari to atone for his involvement with them.
(My favorite B5 bad guy, BTW.)