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

forensic Forensic science combines principles of law and science to investigate criminal activity. Through crime scene investigations and laboratory analysis, forensic scientists are able to link suspects to evidence. An example is determining the time and ...

technique which used

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...

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 enforcement. ...

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

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

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

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

U.S. President The president of the United States (POTUS) is the head of state and head of government of the United States. The president directs the Federal government of the United States#Executive branch, executive branch of the Federal government of t ...

John F. Kennedy John Fitzgerald Kennedy (May 29, 1917 – November 22, 1963), also known as JFK, was the 35th president of the United States, serving from 1961 until his assassination in 1963. He was the first Roman Catholic and youngest person elected p ...

assassination Assassination is the willful killing, by a sudden, secret, or planned attack, of a personespecially if prominent or important. It may be prompted by political, ideological, religious, financial, or military motives. Assassinations are orde ...

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

Federal Bureau of Investigation The Federal Bureau of Investigation (FBI) is the domestic Intelligence agency, intelligence and Security agency, security service of the United States and Federal law enforcement in the United States, its principal federal law enforcement ag ...

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 Nati ...

Board on Science, Technology, and Economic Policy Board or Boards may refer to: Flat surface * Lumber, or other rigid material, milled or sawn flat ** Plank (wood) ** Cutting board ** Sounding board, of a musical instrument * Cardboard (paper product) * Paperboard * Fiberboard ** Hardboar ...

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 language, German: ', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a s ...

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 conviction A miscarriage of justice occurs when an unfair outcome occurs in a criminal or civil proceeding, such as the conviction and punishment of a person for a crime they did not commit. Miscarriages are also known as wrongful convictions. Innocent p ...

s. 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