Nephestis is a Cheftu spy for the Tlakk'ahn. It's his shapeshifting abilities that gives him an advantage. He framed Major Gus Bonner by impersonating him on PR6-308. He tarnished Major Bonner's reputation even more back at Stargate Command by using his stolen image to stun the Stargate technician and Cadet Harrison who was in the control room at the time. He used the technician's DNA to open the iris and activate the Stargate to let the Tlakk'ahn into Stargate Command.