At a press briefing in February 2002 about the lack of evidence of weapons of mass destruction in Iraq linked to terrorist groups, then-Secretary of Defense Donald Rumsfeld offered insightful perspective:
“There are known knowns; there are things we know that we know,” Rumsfeld said. “There are known unknowns; that is to say, there are things that we now know we don’t know. But there are also unknown unknowns – there are things we do not know we don’t know.”
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William A. Tobin is a scientist who spent 27 years as an FBI agent, the last 24 in the FBI Laboratory, and since then has worked on legal cases for both defense attorneys and prosecutors as a forensic metallurgist/materials scientist. He was the principal critic of the forensic practice of comparative bullet lead analysis (CBLA), which has since been discontinued by the forensic community, and has published numerous forensic papers.
Distinguished Professor Cliff Spiegelman, a member of the Texas A&M University faculty since 1987, was a panelist for the National Research Council of the National Academy of Sciences’ committee convened to investigate the challenge to CBLA. He is a leader in the field of statistical forensics and best-known for his joint forensic work related to the President John F. Kennedy assassination bullets, which earned an award from the American Statistical Association (ASA). Spiegelman is an elected fellow of the ASA and the Institute of Mathematical Statistics.
To find a previous article by these authors on the science of forensic evidence, go to this story at statesman.com/insight.