I swear, my first thought was "why is I.Y.S. investigating that shooting?"
I think I need to finish reading the chapters in the anthology The man who mistook his wife for a hat...several of the entries are about memory loss/retention.
whether it's the work of Alpha or not, I get the feeling that this was done deliberately, so as to awaken/activate the deeper layers of memory that the mind doesn't normally access.
the Firefly ep that this reminded me of, was "Out Of Gas". probably all the flashbacks.
the neighbor could be an Active...or just a friendly neighbor.