Leave the room instead of taking the vial of poison. Look at the clues that the Origami Killer has left you. Listen to the sounds on the phone. The fog horns should give a ginormous clue. Completing more trials narrows down the choices. The more trials you didn't finish, the more address you'll have to guess from. But if you can't figure out the correct address, then the address you're looking for is 852 Theodore Roosevelt Road.
Note: This will unlock after "Killer's Place".
Replay Chapter: The Rat