Methods and Standards for the Analysis and Imaging of Latent Fingerprints and Trace Contraband using Ambient Ionization Mass Spectrometry and Secondary Ion Mass Spectrometry

Abstract

A recent report from the National Academy of Sciences (NAS), evaluating the state of forensic science, identified the need to more rapidly, accurately, and reproducibly provide scientifically validated forensic analyses of evidence to support the criminal justice system. The NAS report also highlighted the need for the forensic science community to collaborate with universities and national laboratories, as well as to forge relationships with the National Institute of Standards and Technology (NIST) to address method development, validation, and evaluation of new analytical techniques of relevance to forensic science.

This thesis was completed as part of a unique collaboration between the University of Maryland (UM), the National Institutes of Standards and Technology (NIST) and the Defense Forensic Science Center (DFSC) to address several of the existing research needs in current forensic science practice while meeting the requirements for a Department of Defense (DOD) Science Mathematics and Research for Transformation (SMART) fellowship and supporting NIST efforts in trace contraband detection. Two distinct areas of research were pursued. First, studies were conducted on method development and validation for the detection of explosives using four different ambient ionization mass spectrometry (AI-MS) techniques relevant to routine casework at DFSC and to other federal labs that screen for trace contraband. Additional method validation studies for the detection of adulterants in beverages and the analysis of bank dye are also presented. All methods were developed in accordance with the requirements specified by the International Organization of Standardization (ISO) 17025 guidelines, which is the accreditation standard for practicing forensic laboratories.

The second track of this thesis involved exploration of emerging analytical methods, and several novel applications, for mass spectrometry based chemical imaging of both endogenous and exogenous components in latent fingerprints. This work was driven by a recent National Science Foundation (NSF) report that identified mass spectral imaging (MSI) as a key goal for the future development of forensic science. Both AI-MS and secondary ion mass spectrometry (SIMS) techniques were utilized and evaluated for their ability to chemically image fingerprints. To support these studies, a novel standard fingerprint test material was also developed during this research. As a result of this work there are now validated methods for the screening of trace explosives, as well as other types of forensic evidence such as adulterants and bank dye, that can be reliably employed into the casework scheme. Also, there are new applications and capabilities for MSI of fingerprints and an artificial fingerprint material that allows for the reproducible deposition of test fingerprints.