A rainy night is a natural bug of modern criminal science.
The often mentioned Locard's Principle of Exchange—whenever two objects come into contact, there is an exchange of materials; something is taken and something is left behind—is the foundation of crime investigation science.
The vast majority of forensic techniques follow the Locard's Principle of Exchange. Under this principle, the world is as beautifully logical as elementary mathematics, as if everything is coherent and solvable.
Time delivers a heavy blow to the Locard's Principle of Exchange; as time passes, much evidence gradually disappears and eventually vanishes.
But combating time itself is the part most familiar to and yet most accepted by humanity…
A rainy night is different.
It can wash away evidence and alter the crime scene on the day of the crime.
