This is one of two ways you can complete Mission 6 if you so choose to do so (doing either way will get you the code for Jindosh's lock).
For this achievement, you must kill/knockout Paolo, and bring him to the Vice Overseer, once you do so, he will give you the code to Jindosh's lock. (If you want to do a stealthy playthrough, save, get the code, reload and go through)