Answer:
The answer is "Locard's principle".
Explanation:
In today's federal authorities, the basic principle is formulated by Locard's principle transfer, it is the basic principle, that is "each touch left a trace", Therefore, after leaving traces, no suspect can leave the area.
In this principle, all carry into the picture and leave the area to something. This theory, in many other words, states that any interaction leaving a residue of proof, superficially.