Cliff Spiegelman
Department of Statistics
Texas A&M University
Data Integrity and the Scientific Method:
The Case of Bullet Lead Data
as Forensic Evidence and the JFK Assassination
The FBI has used the chemical analysis of bullet lead as a forensic tool for about 40 years. When a bullet(s) is found at a
crime scene and in a suspect's possession the trace elements in the
bullet can be compared. If the bullets are similar enough a match
is declared. The use of this technique in court testimony is the
subject of a relatively recent National Academy of Sciences (NAS)
report. The NAS report has been covered by national print media,
and broadcast media as well. I will discuss the report from the
point of view of the two statisticians on the NAS panel who wrote
the report. A main point will be that the FBI crime lab needs to
pay more attention to following "the scientific method" in reaching
their decisions. The basic premise of this talk is that sunlight is
good and unnecessary darkness is not. The FBI Crime Laboratory
subsequent to the NAS report has ceased using the compositional
analysis of bullet lead. The issues discussed apply broadly to
forensic science laboratory management.
The second part of the talk will deal with Dr. Guinn's testimony to
the House Select Committee on Assassinations concerning
compositional bullet lead evidence in the JFK assassination.
Based upon joint work with Karen Kafadar, Bill Tobin, Dennis James,
Stu Wexler, and Max Roundhill
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