By Susan Schmidt, The Washington Post
A draft report by government scientists at the National Research Council disputes the validity of an FBI method of matching bullets, potentially calling into question hundreds of criminal convictions that relied on such evidence, sources familiar with the findings said yesterday.
The report faults the FBI’s practice of chemically comparing bullet lead from a crime scene to lead in unused bullets, contending that there is insufficient scientific basis to determine that bullets came from the same batch of lead, the sources said.
The FBI lab has conducted this sort of analysis for decades, and such analyses have often been used to link defendants to weapons used in crimes. The draft report, which remains subject to revision, casts doubt on the statistical data the bureau has used in some trial testimony, the sources said.
FBI laboratory chief Dwight E. Adams asked the National Academy of Sciences to examine the way the bureau analyzes bullet lead last year, after several analysts, including William A. Tobin, one of its former lab scientists, challenged the science undergirding the procedure.
The draft report shares Tobin’s view that bullets from the same box or batch of lead may have highly variable chemical properties, and that a particular bullet may share similarities with bullets from batches produced elsewhere or at other times, the sources said.
A spokesman for the FBI said the bureau had not seen the draft and cautioned that its conclusions are not final. “We have not seen the report. We would want to know how they reached the conclusions they did,” said FBI spokesman Paul Bresson. While he stressed that the bureau itself “asked for the study and paid for it,” he asserted that it believes its bullet comparison methodology is sound. “We’re confident of what we’re doing,” he said.
Bresson also castigated Tobin, saying that while he has criticized FBI scientists for offering testimony in areas outside their fields of expertise, “now he is doing the very same thing.” Bresson asserted that Tobin is not a metallurgical expert.
A spokesman for the Justice Department said officials there have not seen a final report and cannot say what impact it will have on criminal convictions in which such FBI evidence was used.
The council, the main operating agency for the National Academy of Sciences, declined to discuss the draft yesterday after some of its contents were reported by the Los Angeles Times and the Associated Press.