Go left into the west end and check the copiers at PrintFax for clues.
It is the owner of PrintFax, who is never seen without his robber's mask and black clothing.
You get the key for Good Deals when you surprise the robber at MacGuffin's. (He knocks you down at the Costume store.)
There is nothing you can do. When he knocks you down, go and hide at MacGuffin's and you can surprise him.
There are no coins used on Night watch island.
Greet the old lady robot, and warn the kid robot on the escalator (oops). When the robber robot grabs the purse, chase him down.
Obviously the robber put the dummy into cart to distract you. Go back into the left side of the mall. Gus will suggest that you look at PrintFax for a clue.
The one at Good Deal Electronics, just next door to MacGuffin's where you surprised the robber. Use the toy robot by the camera to keep the lights on.
night watch island
After the crash of the dummy, go to the left end of the mall. On the copier in PrintFax, select MENU and "reprint last document scanned."
Back Lot Island (April 2013)
You only get the key at a later point in the quest, when you surprise a robber at Carnival Costumes and MacGuffin's. (You can use the toy robot from Giuseppe's to keep the lights on -- place it by the camera.)
When you are chasing the robber, cut the metal bars (red) with your blowtorch. When you reach the air chamber, the robber will hit you. Go right into the vents, cut the brown metal bars, and use the torch to destroy the AC controls. Now you can cross to the left side of the air chamber, go through the brown bars there, and chase the robber up the left side ladders.