Penitentiary Mansion--Part 1

Inside the Penitentiary, check the table by the entrance for an Interview Tape then take down the trio of inmates ahead (sneak up behind them for at least one stealth takedown). Now use detective mode to follow the DNA trail up to a door that will open.

Inside the Main Cell Block, continue to follow the DNA trail down a hall in the back, through another door, leading to the Green Mile. After speaking with Poison Ivy, proceed through the door in the back into the Security Control Room. Climb the central tower to find Warden and free him.

Gordon will provide you with the Cryptographic Sequencer, allowing you to bypass those darn electric fences finally. Try it out on the nearby control box, at the top of the stairs from the electric fence blocking your exit. After activating the Sequencer, use the control sticks to tune to the proper frequency, disabling the fence. Now head back to the Main Cell Block--a crazed inmate will jump you before you get there, but they're easy to deal with. Just mash the button shown on-screen then use a ground-takedown.