Hair testing is only used by the Federal Bureau of Investigation (FBI) when other information exists that indicates drug use and can remove a person from suspicion or associate them with criminal activity. The detection of cocaine in hair has been the FBI's first priority in hair testing for drugs of abuse because of its prevalence. Several cases when hair testing was used are reported in this chapter. Further, analysis of over 100 samples was performed on hair obtained from a medical examiner's random autopsy collection. Sixty-five percent of the samples tested positive for cocaine or opiates. The results of hair testing for drugs of abuse were found to be consistent with autopsy toxicology reports. The analysis of hair washes and nails from the autopsy samples suggests external contamination of hair with drugs is not widespread.