This is a covered hopper car. Covered hoppers provide the scenes of the crime in the next Steve Martinez novel, Tracking the Beast, coming in December.
Now why would covered hopper cars be useful to a serial killer? You'll just have to wait to find out.
Meanwhile, I am buying that hopper car above to use in library and bookstore presentations. It's a G scale model, about two feet long. That ought to be useful for an author with murder on his mind.