Since when has WA's plot ever been so simple? I'll clarify my previous statment. There's a Tower Rat, we know this. But there's other people around as well. The soldiers and most of the designated leaders of "something" were out of the Tower at the same time. When the Cat's away the mice will play. Riley's food shop, Burt's gun shop, the generator/elevator were all open for just anyone to come in and take advantage of. From what we know of Pegs story she wasn't in there the whole time, so any number of residents could have come in and took a little food thinking it wasn't enough to cause harm. People were unhappy with Michael's leadership at the time remember? If Bill was among the the freeloaders, his apartment was left wide open. The Rat was probably working while everyone else that might be wandering the halls was distracted. Then Tattoo comes and scares everyone back into their apartments. No one's going to come forward and admit to stealing after that incident.