Sorry to hear about the tragic accident. The restroom in question might be the one across from B7 in Terminal 1. There is an exit down to baggage claim nearby, but I don't recall it being located right next to the door. And I know of no (public) stairs that lead to any other place other than the baggage claim.
I'm not familiar with Terminal 2.
Here is a diagram of Terminal 1 from the ORD airport authority:
http://www.flychicago.com/ohare/conc...12008FINAL.pdf
and Terminal 2:
http://www.flychicago.com/ohare/conc...ed11-24-09.pdf
Best regards