Hair and fibres can provide valuable clues about the identity of an assailant or attacker. The discovery of hair on the body of a victim or on the clothes of a victim of an assault can often be used to determine the assailant or attackers' race and sex.
The transfer of human hairs may take place in a wide variety of cases. Common examples involve the transfer of head hairs to hats or balaclavas or the transfer of head or body hairs to clothing and bedding (for example, in sexual assaults), or the transfer of cut or broken hair fragments to an object (for instance, on a weapon used to strike a victim), or even on a windscreen of a vehicle involved in a collision. Occasionally, single head hairs may be found at the point of entry in house break-ins or clumps of hair pulled from a victim of a physical assault can be found on clothing or at the scene.