He should be in AR1105 area (Umar Hills Inn), specific coordinates: 975.160
If you're planning to summon him with a console, do it in that area and make sure he's not there already. The creature name file is "L0THIEF1".
If he wasn't created, the variable should be Global("L0StartWisp","GLOBAL",3), once he's spawned it becomes Global("L0StartWisp","GLOBAL",4), so that's going to tell you if the creature already exists.