FBI Laboratory Announces Discontinuation of Bullet Lead Examinations
|Washington, D.C. September 01, 2005|
Washington, D.C. -- The FBI Laboratory today announced that, after extensive study and consideration, it will no longer conduct the examination of bullet lead. Bullet lead examinations have historically been performed in limited circumstances, typically when a firearm has not been recovered or when a fired bullet is too mutilated for comparison of physical markings. Bullet lead examinations use analytical chemistry to determine the amounts of trace elements (such as copper, arsenic, antimony, tin, etc.) found within bullets. The result of that analysis allows crime-scene bullets to be compared to bullets associated with a suspect. Since the early 1980's the FBI Laboratory has conducted bullet lead examinations in approximately 2,500 cases submitted by federal, state, local, and foreign law enforcement agencies. In less than 20% of those cases was the result introduced into evidence at trial.
In 2002, the FBI asked the National Research Council (NRC) of the National Academy of Science to have an independent committee of experts evaluate the scientific basis of comparative bullet lead analysis. Specifically, the FBI divided the bullet lead examination into three parts (the scientific method, the data analysis, and the interpretation of the results) and asked the NRC for an impartial review of each area. The technology reviewed by the NRC had been used by the FBI Laboratory since 1996. The NRC's recommendations, following the study, were set forth in a report entitled "Forensic Analysis: Weighing Bullet Lead Evidence."
The NRC found that the FBI Laboratory's analytical instrumentation is appropriate and the best available technology with respect to precision and accuracy for the elements analyzed. It also found that the elements selected by the FBI for this analysis are appropriate. The NRC expressed concerns, however, relating to the interpretation of the results of bullet lead examinations.
Following the issuance of the report the FBI Laboratory embarked on an exhaustive 14-month review to study the recommendations, offered by the NRC, including an evaluation of statistical methodologies. Although the NRC stated that the FBI Laboratory did not need to suspend bullet lead examinations while undertaking this review, the FBI elected to do so while the review was pending.
One factor significantly influenced the Laboratory's decision to no longer conduct the examination of bullet lead: neither scientists nor bullet manufacturers are able to definitively attest to the significance of an association made between bullets in the course of a bullet lead examination. While the FBI Laboratory still firmly supports the scientific foundation of bullet lead analysis, given the costs of maintaining the equipment, the resources necessary to do the examination, and its relative probative value, the FBI Laboratory has decided that it will no longer conduct this exam.
Letters outlining the FBI Laboratory's decision to discontinue these examinations are being sent to approximately 300 agencies that received laboratory reports indicating positive results since 1996. The letters are being sent so that these agencies may take whatever steps they deem appropriate, if any, given the facts of their particular case. It is important to note that the FBI Laboratory has not determined that previously issued bullet lead reports were in error.
The NRC's report is available through the National Academies Press website at (www.nap.edu).