When a person comes in contact with other there is transfer of material from one to another. This is called:
Locards principle of exchange states that when two objects come into contact with each other, there is always some transfer of maternal from one to the other. Ref: Parikh's Textbook of Medical Jurisprudence Forensic Medicine and Toxicology, 6th Edition, Pages 5.35, 7.35
Locard's principle
Quetlets rule
Petty's principle
None of the above