Comparative bullet-lead analysis (CBLA), also known as compositional bullet-lead analysis, is a now discredited and abandoned

forensic Forensic science, also known as criminalistics, is the application of science to criminal and civil laws, mainly—on the criminal side—during criminal investigation, as governed by the legal standards of admissible evidence and criminal p ...

technique which used

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...

to link

crime scene A crime scene is any location that may be associated with a committed crime. Crime scenes contain physical evidence that is pertinent to a criminal investigation. This evidence is collected by crime scene investigators (CSI) and law enforcemen ...

bullet A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. Bullets are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax. Bullets are made in various shapes and co ...

s to ones possessed by suspects on the theory that each batch of

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...

had a unique elemental makeup. The technique was first used after U.S. President

John F. Kennedy John Fitzgerald Kennedy (May 29, 1917 – November 22, 1963), often referred to by his initials JFK and the nickname Jack, was an American politician who served as the 35th president of the United States from 1961 until his assassination ...

assassination Assassination is the murder of a prominent or important person, such as a head of state, head of government, politician, world leader, member of a royal family or CEO. The murder of a celebrity, activist, or artist, though they may not have ...

in 1963. From the early 1980s through 2004 the US

Federal Bureau of Investigation The Federal Bureau of Investigation (FBI) is the domestic intelligence and security service of the United States and its principal federal law enforcement agency. Operating under the jurisdiction of the United States Department of Justice ...

conducted about 2,500 analyses on cases submitted by law-enforcement groups. The results of these analyses had often been questioned by defence lawyers and the press, so the FBI finally asked the

United States National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the N ...

Board on Science, Technology, and Economic Policy The United States National Academy of Sciences' Board on Science, Technology, and Economic Policy (STEP) is a board of the United States National Academy of Sciences. The mandate of the Board is to integrate understanding of scientific, technolog ...

to research the scientific merit of the process. In 2004 the Board's study was summarized in "Forensic Analysis: Weighing Bullet Lead Evidence." The Board determined that the chemical analyses were being performed correctly and were probably sufficient to determine correlation between two bullets from separate sources (the analysis used plasma-optical emission spectroscopy to identify trace elements in the bullets). The report also concluded that the seven trace elements selected for the analyses (arsenic, antimony, tin, copper, bismuth, silver and cadmium) are acceptable for sample correlation. The report finally concluded that the procedure is the best available method for such correlations. The greatest caveat in the report was that the

statistical Statistics (from German: '' Statistik'', "description of a state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, industr ...

tests as applied by the FBI could cause confusion and misinterpretation when transmitted to prosecutors or when explained to a trial jury. Because of the significance of this weakness, the report concluded that the analysis should be used with caution. This report helped the FBI decide in 2004 to voluntarily cease offering the analysis to law-enforcement entities. The National Academy of Sciences never required that the FBI stop using the test. ''CNN Presents Encore Presentation: Reasonable Doubt'' examined the unreliability of this technique. It has been discontinued as of September 1, 2005. The U.S. government has fought releasing the list of the estimated 2,500 cases over three decades in which it performed the analysis, which may have led to false convictions. According to the FBI, only 20% of the 2,500 tests performed introduced the CBLA results into evidence at trial. On 17 December 2008, Jimmy Ates was released from a Florida prison after serving ten years on the conviction of having murdered his wife, a conviction obtained largely on the strength of a bullet-lead analysis. His conviction was overturned as a consequence of the 2004 report.

References

{{Reflist Federal Bureau of Investigation Forensic techniques Comparisons

Further reading

References