Trace evidence occurs when objects make contact, and material is transferred. This type of evidence is usually not visible to the naked eye and requires specific tools and techniques to be located and obtained. Due to this, trace evidence is often overlooked, and investigators must be trained to detect it. When it comes to an investigation trace evidence can come in many different forms and is found in a wide variety of cases. This evidence can link a victim to suspects and a victim or suspect to the crime scene.
Close-up of broken fuel pipe using optical microscopy
Droplets of human blood. The droplets are round and show no splattering, indicating they impacted relatively slowly, in this case from a height of two feet.
Dr. Edmond Locard was a French criminologist, the pioneer in forensic science who became known as the "Sherlock Holmes of France". He formulated the basic principle of forensic science: "Every contact leaves a trace". This became known as Locard's exchange principle.
Edmond Locard