The French criminologist, Dr. Edmond Locard, was a pioneer in forensic science, as he formulated that “every contact leaves a trace”. The Sherlock Holmes of France – as he was often called – in his famous principle stated that when a crime is committed, fragmentary or trace evidence comes about. What is a trace evidence? As A Simplified Guide to Forensic Science states:
Trace evidence can be used to link people or objects to places, other people or other objects, and often serves as a starting point, or lead, for a particular line of investigation. Trace evidence helps to put together pieces of the investigative puzzle—from which direction did the perpetrator arrive? How close was the victim to the window when the bullet shattered the glass? Were stolen goods transported in a particular vehicle?
However, I wanted to dig further: what is the difference between trace and track? What are marks, clues or even leads? Let us find out:
1. Trace and Track
As verbs they both imply a reconstruction or identification of a certain path. But, there are differences in their direction and their points in time.
To trace means to follow back a track in time from its current position to its origin. To track, on the other hand, means that you follow a path forward to wherever something is. For example you can trace a phone call back to determine its origin, but you track a phone call to see its current location or where it goes later. Think of tire tracks – they can show where the car went.
As with fingerprints and fingermarks, a mark might represent an impression – something that was left on a surface. For instance, a tool can leave a mark on the surface of a wall.
By definition, clue means: “an object or piece of information that helps someone solve a crime or mystery”. But did you know that, according to Merriam-Webster dictionary, its origin is:
“The word clue was originally a variant spelling of clew, meaning “ball of thread or yarn.” Our modern sense of clue, “guide to the solution of a mystery,” grows out of a motif in myth and folklore, the ball of thread that helps in finding one’s way out of a maze. Of these stories the best known is the myth of Theseus and the Minotaur. In the myth, Theseus unravels a ball of thread as he searches for the monstrous Minotaur in the Labyrinth. After killing the Minotaur, he retraces his steps out of the maze by rewinding the thread.”
If the police have a lead, it can indicate that they have found something that they can start (or even continue their stuck) investigation on. To lead means to guide someone or to direct someone forward, hence a lead helps investigators to go on with their cases. A new witness, or a new piece of evidence can serve as a lead in their investigations. In a way, a lead might help you find a clue to solve a mystery.