Yeah, use poisonous cloud, just don't target directly at him, because you won't be able to attack him, target a bit in front of him or behind him.
This is also how you can kill a lot of friendly NPCs, if they annoy you, without being blamed/attacked by guards. I killed Commander Kratus this way, after I solved Tutamun quest and before I stole magic lockpicks and Penumbra's dagger...it annoyed me when he caught me stealing. After killing him this way I could just walk in the station and pick up everything my heart desired... <img src="/ubbthreads/images/graemlins/biggrin.gif" alt="" />
