The shapeshifter is disguised as a wookie... i forget his name. He's in the upper shadowlands in plain sight, but you have to pick up the datapad of the ground a little ways in front of him. It tells you about a wookie who died, and the shapeshifter is disguised as that same wookie, so now you can call his bluff. Hope that helps.
Some who have recieved life deserved death, and some who have recieved death deserved life... can you give it to them?