FBI Bullet Analysis Technique Invalidated With Science

Hugh Pickens writes "The Washington Post reports that the FBI has abandoned comparative bullet-lead analysis, the technique using chemistry to link crime-scene bullets to ones possessed by suspects. The comparison was made on the theory that each batch of lead had a unique elemental makeup. The National Academy of Sciences has revealed that decades of FBI statements to jurors linking a particular bullet to those found in a suspect's gun or cartridge box were so overstated that such testimony should be considered 'misleading under federal rules of evidence.' NAS says that the flaw is in using a statistical method called chaining (pdf). Analysts sequentially compared crime scene bullets to a set of reference bullets ... which can lead to the formation of artificially large sets of matching bullets. The government has fought releasing the list of the estimated 2,500 cases over three decades in which the FBI performed the flawed analysis."