[ Register or Signin to view external links. ]

This achievement is highly missable. It is earned over the course of a single playthrough, particularly during Mission 4, The Clockwork Mansion, and Mission 6, The Dust District.

The first opportunity you will have to kill Paolo is during Mission 4, The Clockwork Mansion. Upon visiting the Black Market shop, the storekeeper will ask that you return at a later time due to a visitor who is on their way. Be quick and hide anywhere in the room (on the rafters or underneath the nearby table). Paolo will soon appear alongside a few Howlers and this is where you'll want to take him out, only to realize his dead body transforms into a flood of rats.

The second and third opportunity to kill Palo is during Mission 6, The Dust District. Your objective during this mission is to make it past the Jindosh lock leading to Aramis' manor. The Howlers or the Overseers can aid in solving the riddle shielding the lock should you deliver the body of the opposing faction's leader. Naturally then, Paolo will be marked as a primary objective on your HUD. Head to the Howler's territory, enter the saloon, and kill Paolo and all of his gang mates. After you kill him, he will turn into a swarm of rats again and respawn upstairs near his shrine. Track him down, kill him one last time (which will put an end to him for good), and the achievement will finally unlock.

NOTE: This achievement is best saved for the lethal High Chaos playthrough, as killing Paolo will void the "Clean Hands" achievement.