The episode is called Aubrey, and you only see Agent Sam Chaney for two very brief scenes. Once as a picture on a report Scully holds near the camera, and once in a flashback B.J. Morrow has. He looks like actor Jeffrey Combs to me, but its not listed in his filmography, and the actor for Sam Chaney was uncredited in the show.
Can someone confirm my suspicions, or else tell me otherwise? Thanks.