This guy is hiding in Alma, to the west of the fuel station, in a shack. Talk to him, kill him, travel back to Cambria and talk to Carmen.
TIP: if you have a spare Merc, leave them in cambria while you do these quests so, when you complete it you can instantly get the next quest instead of walking back and forth wasting game time.
Quest - Intercept's Most Wanted #3
Quest Pickup - Cambria (I15) (Carmen)
Quest Location - Alma (A22 Map2)
Quest Finish Point - Cambria (I15) (Carmen)