Before the 19th century, witness testimonies were viewed as the ‘smoking gun’ during court proceedings. In the 1930s, French criminologist and forensics pioneer Dr. Edmond Locard outlined his theory of exchange in the American Journal of Police Science (Solanki, 2013). Locard’s exchange principle was derived from the concept that if one makes contact with another person, place or thing, physical materials are inevitably exchanged. Therefore, when applied to a crime scene, a criminal cannot commit a crime without leaving some form of evidence, while simultaneously taking some form of the crime scene away with them, even if only on a microscopic level (Solanki, 2013). Today, Locard’s exchange principle is most commonly referred to as trace evidence
