How to Get the 'Serial Killer' Achievement in Batman: Arkham City

I've been pretty straight forward with my praise for Batman: Arkham City. But the thing I like most of all are all of the side missions in the game. One of the cooler, and darker, ones is entitled Identity Thief. No, you don't go after some nerd that hacks people's credit card information. You go after a psychopathic serial killer.

Check out the video below for a great walkthrough of the whole sidequest. While I haven't gotten far enough in the main campaign to initiate the Identity Thief side mission, this video is making me seriously reconsider my weekend so that I can get this thing started.