The comparative bullet-lead analysis, which is one of FBI’s forensic tests, seems like it has lead to the arrest of hundreds of innocent people related to serious gun related crimes. The test was discarded some two years ago, due to the fact that the certain technique that it was using was found as unreliable, but FBI did not alert neither the inmates nor the courts.

The fact was put in the public attention by a joint investigation of The Washington Post and 60 Minutes, which criticized the FBI, especially because now it might be too late for the imprisoned, since the period of time in which they could have done an appeal is close to its end.

The test used a comparative bullet-lead analysis that was inaugurated after United States President, John F. Kennedy was assassinated in 1963. It linked crime scene bullets to the ones that the suspects possessed through chemistry, on the principle that batch of lead had a unique elemental makeup.

However, in 2004, the National Academy of Sciences demonstrated that the test was not conclusive, since the variations in the process of manufacturing the bullets could tangle FBI’s test.

The Academy stated that the accusatorial testimonies that were made based on the forensic test should be considered "misleading under federal rules of evidence", since there are many risks for them to be false.

The investigation also showed that FBI was aware of the National Academy of Sciences’ analysis, but it did not make any steps in clarifying the issue, under the reason that they did not support any other results of the tests as an official proof against those who are charged.

The government did not accept to make the list of the estimated 2,500 cases over three decades which were based on FBI’s test.

As a response to the investigation, FBI began working with the Department of Justice in order to let anybody who was affected by the forensic tests know about the mistake.