In crime scene investigations, a single strand of hair can make a huge difference in the evolution of a case or trial. In most cases, forensic scientists must look for clues hidden in minuscule amounts of substances or materials found at crime scenes. If a fallen strand of hair with root cells attached is found, a DNA test can reveal the identity of a criminal; unfortunately, this seldom happens. Even though other types of DNA analysis can be conducted using the mitochondrial DNA embedded in the hair shaft itself, such tests are not sufficient to reliably identify a person and usually call for additional evidence.