At first I did not like your connection-to-someone in neighborhood theory since when I was young, I did not know anyone who would give me or anyone I knew a key or on-my-own access to their place.
But then I thought that I was not a near-homeless teenager willing to trade drugs, shoplifted goods or even sex for a place to sleep.
Welch, with his alcoholic father killing his mother in a car wreck, had a rough childhood, but does anyone know if Welch was sexually abused when young (which often teaches them to do the same years later) or if Welch was bisexual (it's almost always a man doing the abuse)?
I could see some homosexual letting Welch sleep on his couch and bed. I can't really see someone with enough on the ball to have an apartment being Welch's lookout for houses to rob. But this is just a theory.