Just Gunshot Acoustics Research

In this special release episode of the 2017 NIJ R&D Symposium, Just Science interviews Dr. Rob Maher.

Below is the abstract submitted where Dr. Rob Maher explains his research:

Gunshot acoustics–interpretation of the characteristic sounds produced by firearms recorded at a crime scene–is a specialization within the audio forensics field. Audio forensic evidence is increasingly common in law enforcement investigations because of the growing availability of inexpensive and lightweight digital voice recorders and miniature personal digital video camera systems for routine law enforcement and surveillance use. An increasing number of cases involving gunshot sounds are being captured in these audio recordings. The acoustical characteristics of a firearm depend upon the type of gun and ammunition, the distance and azimuth with respect to the gun barrel, and the acoustical reflections and reverberation due to nearby surfaces and objects. For scientific study it is necessary to separate the direct sound of the muzzle blast from the acoustic reflections, echoes, and reverberation that depend upon the recording environment. We use an elevated array of twelve specialized microphones capable of capturing the high intensity and short duration of the firearm’s muzzle blast concurrently over 180 degrees in azimuth. Each microphone is recorded with 16-bit resolution at a 500 kHz sampling rate, and the elevated platform allows the entire muzzle blast to be recorded before the arrival of the first acoustical reflection from the ground. This presentation includes a description of the firearm recording technique, the characteristics observed from these scientific recordings, recommendations on the use and processing of our database of firearm acoustical recordings, and a discussion of future prospects for forensic gunshot acoustical analysis.

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Dr. Rob Maher joined the Montana State ECE faculty in August, 2002. He holds a BS degree from Washington University in St. Louis, an MS degree from the University of Wisconsin-Madison, and a Ph.D. from the University of Illinois-Urbana, all in Electrical Engineering. His research and teaching interests are in the area of digital signal processing, with particular emphasis on applications in digital audio, audio forensic analysis, digital music synthesis, and acoustics. Dr. Maher became ECE Department Head on August 1, 2007, and served in that role for ten years.

Dr. Maher was a faculty member with the Department of Electrical Engineering at the University of Nebraska-Lincoln, from 1989-1996 (tenured in 1995). He joined EuPhonics, Inc., of Boulder, Colorado, in 1997, and was named Vice President of Engineering. When EuPhonics was subsequently acquired by 3Com Corporation in November, 1998, Dr. Maher remained with 3Com-U.S. Robotics as Engineering Manager for Audio Product Development until July, 2001. He also started a successful audio software engineering consulting company (2000-present), and he has been an Adjunct Associate Professor of Electrical and Computer Engineering with the University of Colorado-Boulder (2001-2002). Read More on Dr. Maher’s Montana University Faculty Page.



Just Postmortem Interval Estimation Research

In this special release episode of the 2017 NIJ R&D Symposium, Just Science interviews Dr. Jeffrey Wells and Dr. Lynn LaMotte.

This is the abstract submitted where Dr. LaMotte and Dr. Wells explain their research:

To our knowledge an estimate of time since death is almost never accompanied by the kind of mathematically explicit probability statement that is the standard in most scientific disciplines. This has been a problem both for death investigation casework (and court testimony) and for research, because scientists have not known how to design decomposition experiments to provide adequate statistical power for postmortem interval (PMI) estimation. We have been developing methods for calculating statistical confidence limits about a PMI estimate based on either continuous quantitative or categorical data. The examples we present are from forensic entomology, but the approach is suitable for any postmortem variable. To do this we extended and adapted the time-tested statistical method of inverse prediction (IP, also called calibration) to the PMI estimation setting. Methods to produce valid p-values for this process are known for single, quantitative y and x that follow a linear regression relation and with y having constant variance. Some exist for multivariate y, but only for settings where y has constant variance. Many measurements used for PMI estimation do not fit these criteria. The current project builds on earlier work in which we developed IP methods for non-constant variance of a single, quantitative y (e.g. estimating carrion maggot age using a single size measurement, Wells and LaMotte 1995), and in which we developed the first ever method for IP based on categorical data (e.g. estimating PMI based on carrion insect succession, LaMotte and Wells 2000). One possible barrier to the adoption of these new inverse prediction methods by researchers and death investigators has been that they are not implemented in statistical software packages. In this presentation we will show how IP using categorical data can be done by simply reading a table. Concerning quantitative data we will show how inverse prediction of PMI can be performed using statistical analysis software already widely available for general linear mixed models, where the statistical theory and methodology are well-established. We will show how flexible models using polynomial splines can be fit for both the means and variance-covariance matrices, and how to use dummy variables over a grid of values of x to get the p-values required for confidence sets automatically. Attendees familiar with mixed models and their applications will be able to implement these methods in standard statistical packages.

Statistical Methods for Combining Multivariate and Categorical Data in Postmortem Interval Estimation
Lynn R. LaMotte,1 and Jeffrey D. Wells2 1Biostatistics Program, LSU School of Public Health

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Watch Dr. Wells’ presentation at the 2017 NIJ Grantees Symposium

Lynn Roy LaMotte, Ph.D., is Professor of Biostatistics at LSU Health – New Orleans.  He has collaborated with Jeffrey Wells, Ph.D., for twenty-five years, striving to address the statistical questions and problems that arise in time-since-death investigations.  This has entailed adapting extant statistical methodology and developing new theory and methods, resulting in novel contributions for statistical inference in models for both continuous multivariate responses (like length and weight) and discrete multi-category responses, such as development stage.




Jeffrey Wells is an Associate Professor in the Department of Biological Sciences at Florida International University, where he is also affiliated with FIU’s International Forensic Research Institute.  He has been active in death investigation casework and research since the late 1980s, and during almost all of that time he collaborated with Lynn LaMotte on the development of statistical methods for estimating time since death.  However, he is an expert on carrion insects and forensic molecular biology and not a statistician. Instead his role has been to direct Dr. LaMotte to the important statistical research questions, and then to interpret the results for the broader forensic science community. View Dr. Wells’ Research Gate Site.

Just Bath Salts 

In this special release episode of the 2017 NIJ R&D Symposium, Just Science interviews Lindsay Glicksberg, a student from Sam Houston State University.

This is an excerpt from the abstract submitted by the guest, Lindsay Glicksberg explaining the research discussed in this episode:

The ongoing proliferation of designer drugs present a variety of public health and safety concerns. Synthetic cathinones are capable of producing a variety of psychostimulant effects. According to the National Forensic Laboratory Information System (NFLIS), their use has escalated. Forensic laboratories must be able to identify these new drugs as part of antemortem and postmortem toxicology investigations. Due to limitations in immunoassay-based screening technologies, many forensic toxicology laboratories must rely on chromatographic-based screening approaches in order to detect these drugs in biological evidence. The detection of drugs is heavily dependent upon the stability of the drug in biological matrices, information that is relatively limited for synthetic cathinones. This research presents a validated method for the quantification of twenty- two synthetic cathinones in urine and blood using liquid chromatography/quadrupole time of flight mass spectrometry (LC/Q-TOF-MS). The validated method was used to systematically evaluate the stability of synthetic cathinones in blood and urine over a six-month period. Drug stability was assessed in terms of pH, temperature, matrix, concentration-dependence and chemical properties.

Abstract Title: Stability of Synthetic Cathinones in Biological Evidence
Award #: 2013-R2-CX-K006
Forensic Discipline: Toxicology
Authors: Lindsay Glicksberg, BS*, Sarah Kerrigan, PhD

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 Lindsay Glicksberg, a PhD Candidate from Sam Houston State University. To learn more about Glicksberg please visit Sam Houston State Blog.

Also you can watch Lindsay’s No Cost NIJ R&D Symposium presentation. 

Just One Pot Methamphetamine

In this special release episode of the 2017 NIJ R&D Symposium, Just Science interviews Dr. Jarrad Wagner from Oklahoma State University.

This is the abstract submitted by the guest where he explains the research him and his team are conducting:

The One Pot methamphetamine production method has become the primary method of choice in clandestine drug laboratories across the United States, due to its simplicity and the availability of required materials. While the method is simple, it also generates risk to innocent bystanders within the community from flammability and toxicity hazards. This study was undertaken to determine the feasibility of the detection of methamphetamine clandestine laboratories through monitoring waste water effluents. Methamphetamine was produced by the One Pot method and the methamphetamine hydrochloride product was filtered out. The remaining materials were deposited into a local waste water system in a controlled setting to simulate the disposal of unwanted production products. Water samples were collected post-distribution to determine a time course and analyzed via solid phase extraction with liquid chromatograph-tandem mass spectrometry. Methamphetamine, pseudoephedrine, and ephedrine were all detectable in the waste water. Also, an over-reduced product characteristic of the One Pot synthesis, CMP [1-(1′,4′-Cyclohexadienyl)-2-methyl-aminopropane] was detected. This work demonstrates the possibility and potential for analyzing waste water to monitor and detect clandestine One Pot methamphetamine laboratories within a community.

One Pot Methamphetamine Effluent Characterization Authors: Jarrad Wagner*^, Matthew Green*, Austin Ciesielski*, David Pretorius** Affiliations: *Oklahoma State University CHS, Forensic Toxicology and Trace Laboratory ** U.S. Department of Energy, Savannah River National Laboratory ^Presenter

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Jarrad Wagner’s 2017 NIJ R&D Symposium Webinar

Dr. Jarrad Wagner is a Professor of Forensic Sciences at Oklahoma State University Center for Health Sciences (OSU CHS), where he specializes in research and instruction in Forensic Toxicology and Trace Analytical Chemistry, including post-blast investigations and clandestine laboratories. He is also the Director of the Forensic Toxicology and Trace Laboratory (FTTL) at OSU CHS, where his principal focus is working with triple quadrupole LC/MS/MS instruments and supporting forensic and clinical laboratories in method development, validation and training.

Professor Wagner formerly served as a Chemist in the Hazardous Materials Response Unit of the FBI Laboratory, where he specialized in crime scene investigations involving hazardous materials throughout the world. Prior to the FBI, his law enforcement experience includes his time as a Forensic Scientist in the Toxicology section of the Orange County (CA) Sheriff-Coroner’s office and his service as a Reserve Police Officer in the City of Irvine, CA. Dr. Wagner earned a Ph.D. in Environmental Toxicology from the University of California at Irvine and undergraduate degrees in Biology and Chemistry.


Additional Content:

School of Forensic Science OKState

OKState Lab Homepage

NIJ Crimes and Prevention Page