Issues in Explosives Residue Analysis: Conclusion

Issues in Explosives Residue Analysis A Primer for the Bar Frederic Whitehurst, Ph.D.[1]

[Editor’s Note: This is a multi-part series deigned to educate the defense bar on important issues concerning explosive and explosive residue investigations]

Part 1: Introduction

Part 2: Back to the Basics: Was it the result of an explosive device in the first place? How do we know that?

Part 3: Daubert provides guidance and a means to expose limitations and evaluate explosive investigations, methods, and interpretation

Part 4: The Explosion Crime Scene: Sampling and Homogeneity Issues

Part 5: Disposition Homogeneity in explosive scene investigation

Part 6: Contamination and Cross Contamination in explosive scene investigation

Part 7: Contamination by “Render-Safe” acts of explosives

Part 8: Transportation and storage of evidence in explosive scene investigation

Part 9: Chemical analysis in explosive scene investigation

Part 10: Identifying Techniques in explosive scene investigation

Part 11: Interpretation of data in explosive scene investigation

Part 12: Experience: What makes for a proper expert in explosive scene investigation?

Part 13: Conclusion

The Supreme Court’s ruling in Daubert has given the trier of fact ways of analyzing the meaning of one of the most complex areas of forensic analysis, explosives residue analysis. Requiring relevancy and reliability addresses issues of contamination, reporting of data, experience, adherence to established protocols, and validation of hypotheses. An extremely complex area of analysis is reduced to a set of questions which the bar and the trier of fact can demand answers to from the expert presenting interpretation of results. Answering these questions is necessary before hypotheses can be validated and therefore presented as opinions. If there are valid answers to these questions from the expert under review on the stand then the opinion being presented to the trier of fact will be helpful and therefore allowed under the Federal Rules of Evidence.

Counsel must especially keep in mind the following checklist of issues to be addressed:

1. Contamination: Explosives residues can often not be seen and therefore contamination of evidence or cross-contamination of crime scenes can take place without the knowledge of the investigator at such scenes.

2. Aberration: Are there other reasonable explanations for the presence of materials which are detected during analysis of evidence from crime scenes or are the chemical species which are detected abnormal in the matrix in which they are found.

3. Absence of material: Explosives function during an explosion chaotically by decomposition and chemical reaction and may during an explosion or even without exploding react with materials in the matrix they are initiated in. It is very reasonable that materials may have been present in a bomb which are completely missing from evidence analyzed either because they have decomposed or not been deposited on the evidence analyzed. Can the expert then, within a reasonable degree of scientific certainty, discount the fact that explosives not detected in residue were not present in the original explosive?

4. Expertise: The explosives crime scene investigative team is made up of many individuals with different training and education levels, with little crossover of skills. Counsel should look closely at the credentials of these team members before they are brought forward as “experts.”

The forensic explosive residue examiner must not forget the reason the court wants his expertise. As so well stated in Justice White’s dissent in U.S. v. Wade [142] “Law enforcement officers have the obligation to convict the guilty and to make sure they do not convict the innocent. They must be dedicated to making the criminal trial a procedure for the ascertainment of the true facts surrounding the commission of the crime. To this extent, our so-called adversary system is not adversary at all; nor should it be.”

However if as a result of lack of training or experience, or because of the pressures described by Starrs and Hodge [143] and bias described in Regina v. Judith Theresa Ward above, the testimony that is offered is questionable, counsel should be able to detect this and protect the trier of fact from it. This paper has been presented to assist in that effort.


[1] Executive Director, Forensic Justice Project, Washington, D.C., B.S. Chemistry, 1974, East Carolina University, Ph.D. in Chemistry, 1980, Duke University, J.D., 1996, Georgetown University School of Law. (202)342-6980.

[142] United States v. Wade, 388 U.S. 218, 229 (1967).

[143] Starrs, supra note 107.


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