A joint investigation by The Washington Post and “60 Minutes” has found that hundreds of defendants sitting in prisons nationwide were convicted with the help of an FBI forensic tool that was discarded more than two years ago, but the FBI lab hasn’t taken any steps to alert affected defendants or courts, even while the window for appealing convictions is closing.
Comparative bullet-lead analysis was first used after President John F. Kennedy’s assassination in 1963 (which probably should have been a clue as to how effective it was). The scientific technique used chemistry to link crime-scene bullets to ones possessed by suspects, based on the theory that each batch of lead had a unique elemental makeup.
In 2004 the nation’s most prestigious scientific body concluded that variations in the manufacturing process rendered the FBI’s testimony about the science “unreliable and potentially misleading.”
The National Academy of Sciences determined 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.” One year later the bureau abandoned the analysis.