In an episode of Major Crimes the killer kept one receipt that provides an alibi for his son. Captain Rader asks to see his wallet and seeing no other receipts asks what was special that he saved this one and only ths one?
In an episode of Castle the killer gives himself away by being able to recall in detail, not just where and what he was doing at one time, but at three different times.
That brings us to unique ways criminals could give themselves away to Superman by preparing for Superman.
Here is one example from an AmeliaFaulks's Superman fanfic
Roman Holiday He swept his gaze left and right. Well, this was interesting. His x-ray vision worked perfectly on the buildings either side, just not on the warehouse directly underneath. Lead-lined roofing was not suspicious in and of itself- entire streets in Metropolis carried it. But to have one warehouse in particular, the only one amongst a complex of otherwise identically constructed buildings, be the odd one out- that was a concern.
So can we think of some other ways criminals can give themselves away by preparing for Superman?
