Natural and unnatural hair loss as detected in the forensic context

Abstract

Hair forms a distinctive characteristic of all mammals, and while animals probably remain relatively indifferent to their hair the same cannot be said of humans. Whole industries are devoted to hair, its grooming, its loss or its unwanted presence. Forensic hair examiners are equally interested in hair for its probative value as it forms associative evidence of a crime, a suspect or a victim. On average, human scalp hair is lost at the rate of 100–200 hairs per day – this is normal hair loss and occurs through brushing, washing, etc. The innate structure and physiology governing human hair growth can tell the forensic scientist many facts. Such facts include whether the hair was lost naturally or was forcibly removed; whether nuclear DNA analysis can be successfully performed; the treatment the hair has undergone and any disease condition of a particular hair. Based on research involving transfer and persistence of hair lost naturally, hair evidence enables the scientist to establish a possible timeline connection with the crime committed. Using a simple microscope, the questioned hair is viewed and is sufficient to indicate if the item is “actually hair”; if it is animal or human hair; the growth stage of the hair and the best approach to analysing the hair from a forensic perspective. This is a simple step that takes only a few minutes and requires simple equipment.