Issues in Explosive Residue Analysis: Contamination by “Render-Safe” acts of explosives

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

Often evidence is received by the forensic explosives expert that has originated from bombs that have been “rendered safe” by explosives ordnance demolition technicians. “Render-safe” operations are first and foremost concerned with the safety of personnel as opposed to the collection of evidence as they should be. Devices used to render safe usually are designed with explosives/energetic materials as part of the device itself. These devices are those that incorporate gun powder propellant to project an object against the unexploded bomb in order to open it possibly without exploding it. Sometimes military explosives are attached directly to bombs to detonate them. Rendering a device safe can leave residues on the evidence which originated from the render-safe mechanism. Another issue arises when render-safe operations take place in specially designated areas which have been utilized in the past for the same purpose. The ground in these areas can be highly contaminated with explosives residues. Those residues can deposit on the evidence and result in misleading interpretation of the data unless the residue analyst has been made aware of the method used to render the bomb safe.

As the reader can see, the collection of evidence in this area can result in residues present on evidence which could lead to misinterpretation of the significance of data. In order for the court to determine if the scientific testimony or evidence admitted is even relevant, the court needs to know if proper controls were in place at the crime scene. (After all, of what relevance to the court and trier of fact are explosives residues that came from the bombing crime scene investigator’s explosives bunker and were placed on the evidence.) This relevance can only be established through the laying of proper foundation testimony. Questions concerning the implementation of proper protocols, gathering of control samples and proper transportation of evidence must be asked. The court must, in reviewing analytical data, look specifically at the data to determine if instrumental output exists from analysis of control swabs that would prove the bomb technician did not unknowingly bring explosives residues into the crime scene. The court also needs to review the testimony of the expert to determine if improper inferences are being drawn from the data.

The field of explosives residue analysis is essentially still in its infancy with many questions left unanswered. Yinon and Zitrin [59] describe the field, “The analysis of explosive residues, usually carried out in forensic laboratories, is a relatively new area. The first studies were published in the 1960s and the number increased in the following decades, coinciding with the spreading use of explosives by terrorists.” Validated protocols do not exist at this time which describe proper explosives residue evidence to be collected at all bombing crime scenes in order to reasonably establish what the explosive main charge was in the bomb.

Small devices used to explode mailboxes present somewhat controlled situations which can reasonably be tested. But large bombs such as those used in the World Trade Center present a completely different fingerprint of residue each time they are exploded. Until protocols are established and properly followed, testimony concerning explosives residue analysis must be very closely reviewed by counsel.


[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.

[59] Yinon & Zitrin, supra note 12, at 163.