I remember a story from back in the late 90s when they started the asset seizure program - a guy who had purchased a car at a government auction was stopped at one of those DUI checkpoints and they had a dog that found a compartment in the trunk with either drugs or drug residue. He was busted and claimed neither he nor the gubment folks who sold him the car had any idea.
I don't remember the outcome.
What if the secret compartment was built to hide his smokes from his wife? Or to stash his gun when he enters City Hall to pick up some papers. Or hide chocolates in there for his mistress?
I remember another case when a innocent man was convicted. He escaped. Later was proved innocent of the original crime but had to serve time for the escape.