Forensic Science Institute

Tag: research – Page 3

Research: Analysis of the Composition of Vehicle Tires using Pyrolysis-Gas Chromatography/Mass Spectrometry

Trace and residue evidence is commonly collected at crime scenes and submitted to the laboratory for analysis with the intention of linking a perpetrator to a particular crime. Although a significant amount of time and effort has been put into capturing vehicle tire tread patterns, little research has been published on the characterization of individual tire compositions. Tire manufacturing is a complex process, and the final product is made from of a variety of different ingredients, with rubber being the most abundant constituent (Bodziak, 2008;Williams & Besler, 1995) The three most common rubber components are natural rubber (NR), 1,3-butadiene (BR), and styrene-butadiene (SBR), with most every tire containing a combination of some or all of these materials (Ding & Liu, 1989; Sarkissian, 2007). Microscale sealed vessel pyrolysis-gas chromatography-isotope ratio mass spectrometry (MSSV-Py-GC/IRMS) can be utilized to separate and identify components of tires. The purpose of this project is to determine the variability in polymer composition among brands of tires, different product lines from these brands, and from different locations on a single tire.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Detection and Identification Techniques for Condom Residues in Sexual Assaults

This study investigated techniques used to detect and identify condom residues in sexual assaults.  There were 10 condom brands/sub-brands analyzed, which were chosen based on the geographical locations of the manufacturers.  Polarized light microscopy was implemented as an initial means of detecting condom residues by identifying common particulates added during production.  It was found that starch was present in only 5 of the condom brands/sub-brands, and no other particulates were identified.  These results led to the conclusion that this technique would not be effective as a general screen for the presence of condom residues.  Gas chromatography/mass spectrometry (GC/MS), coupled with liquid-liquid extraction and later solid-phase microextraction (SPME) were explored with the intentions of building a database that could suggest a condom brand in the instance of an unknown source. Alkaline extractions were conducted on condom residues and in some instances, derivatization was performed.  Analysis revealed that SPME, using a polyacrylate fiber, produced satisfactory results.  This technique produced total ion chromatograms with distinct variations between condom brands and some of the sub-brands, while the mass spectra identified multiple components in the residues.  Isotope-ratio mass spectrometry (IRMS) was also undertaken to determine if the carbon isotopic ratios of condom residues differed among brands.  Three different ratios were observed, suggesting the possibility that manufacturers obtain their lubricants, polydimethylsiloxane, from different geographical sources.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Church Shooting in the United States

In recent years, Americans have been shocked by the increasing number of mass murders occurring in and around churches in the U.S.  Research has formerly examined characteristics of school shooters, workplace shooters, or grouped an excess of varying incidents into the broad category of mass murder, but the behavioral study of church shootings is extremely limited.  It is proposed that research be conducted into incident analysis and the common behavioral characteristics of church shooters to determine if a profile can be developed which will aid in understanding and dealing with those who chose to target churches and their members for extreme and indiscriminate violence.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Maternal Filicide

Incidents of mothers killing their own children are becoming more commonplace in the U.S.  In fact the U.S. ranks the highest of any developed nation in maternal filicide.  The literature on filicide is inadequate to determine relevant risk factors for maternal filicide.  It is proposed that an in-depth analysis of maternal filicide be undertaken to examine the childhood dynamics and common behavioral characteristics of the filicidal mothers, and determine which childhood factors and behaviors may be relevant to risk prediction.

Posted on April 16, 2019 by Dr. Mark McCoy

Service Learning and Forensic Science: The Oklahoma Tornado Victim Project

During the afternoon of May 24, 2011, several large tornados touched down in Oklahoma killing at least ten people and leaving a path of damage fifty miles long. Not only were lives lost, but also computers and other digital devices were severely damaged leaving victims without access to pictures, documents and other vital data stored on these devices. Digital Forensics students, using the knowledge and skills they learned in class and the same high-tech equipment used to solve crimes were able to recover gigabytes of treasured memories and important documents for tornado victims. This service-learning project provided a rich learning experience for students, integrated meaningful community service and strengthen ties with the community.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Extraction and Quantification of Mitochondrial DNA from Human Hair Extensions

This study seeks to utilize current extraction techniques and detection technologies to recover, quantify, amplify, and sequence mitochondrial DNA (mtDNA) from processed human hair extensions and to determine if the grade or quality of the hair extensions affects the results.  In addition to isolating and sequencing mtDNA, this study will seek to differentiate between a processed human hair extension and a real human head hair based on physical, optical, and chemical attributes. For comparative analyses between the processed human hair extensions and real human head hairs both a stereomicroscope and an inverted research microscope will be used to determine if there are any significant physical or optical differences. Chemical analyses will also be conducted to identify the presence of processing chemicals used in the manufacturing of the extensions.  Possible instrumentation for chemical evaluation includes solid phase micro-extraction (SPME) or liquid-chromatography mass-spectrometry.  The detection of these chemicals may allow for the identification of a human hair as an extension and may also link an extension back to the manufacturer.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Approaching Objectivity in Firearms Identification: Utilizing IBIS BULLETTRACE-3D’s Sensor Capturing Technology

Firearm examiners are often asked 1) can bullets be matched back to cartridge cases? 2) What bullets leave suitable markings? 3) Does an objective approach for interpreting firearm examiner conclusions exist? The inability to objectively answer questions related to linking evidence and source in firearm and tool mark analysis suggests the need for further studies that offer appropriate, reliable conclusions. The purpose of this study was to provide an objective approach for interpreting Firearm examiner conclusions. A fixed-bin analysis consisting of 53 bins in a side-by-side representation was utilized to analyze regions of interest on a single bullet’s bearing surface acquired in 1.6mm (band) increments by the IBIS BULLETTRAX-3DTM system. Results address concerns that have been outlined by the National Research Council (2009).  Major findings in this study indicate the IBIS BULLETTRAX-3DTM system can assist examiners with better visualization and the ability to provide objective conclusions in bullet comparisons.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: The Use of Image Analyzing Software for Muzzle to Target Distance Determination

Muzzle to target distance can be an important aspect in criminal investigations. For most distance determination opinions to be of value to an investigation, the range must be stated such that it gives meaningful information and the resulting bracket of muzzle to target distance must also be defended during courtroom testimony. Current measurement tools lead to subjective opinions by examiners. With objective measurements, examiners can provide improved investigative conclusions that may be defended in court with quantifiable data. Due to the rapid advancement in software technology in recent years, the ability exists to analyze targets with more accurate measurements. Currently, test targets are measured by approximate methods that utilize a high degree of subjectivity. This study examined the application of Image J, image-analyzing software, for use in determining muzzle to target distance. This research examined objective data to include particulate density and Gunshot residue dispersion and carried out a statistical replicate study to determine the number of targets needed at a given distance for each gun and ammunition combination. One pistol, revolver, rifle and shotgun were selected for this study. Test targets were shot five times at distances of: 4, 8, 12, 16, 20, 24 and 28 inches for the pistol, revolver and rifle, and at distances of: 4, 8, 12 and 16 feet for the shotgun. Visual and chemical examinations were performed on test targets using standard protocol procedures, published through the National Institute of Justice (NIJ) Distance Determination Training Module (2011). The targets were digitally photographed through each step and analyzed using the aforementioned protocol and Image J, image-analyzing software. Comparisons were made between the National Institute of Justice model and Image J. Data were obtained and reported using the image analyzing software for particulate count and GSR dispersion.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Comparative Analysis of Techniques for Shooting Trajectory Reconstruction

The field of shooting trajectory reconstruction is a common practice for law enforcement investigating crime scenes, though little history is actually known about the field.  It is proposed that this study will advance crime scene knowledge of the field by applying common geometric principles and modern day crime scene reconstruction techniques.  Through comparative analysis, this project will determine beneficial aspects of modern techniques.  The study proposes a comparative analysis of two shooting scene reconstruction techniques; specifically, comparing the use of the Smart LevelÔ and calculations utilizing an angle finder to determine the efficiency of each technique.  These aspects along with statistical data from crime scene investigators will contribute to the accuracy, precision, and error rate for both tools.  This comparison and analysis will provide law enforcement with research enabling them to choose the most effective tool for crime scene analysis and aiding in validating the field of shooting trajectory reconstruction.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: The Effects of Commercial Cleaning Agents on Automated DNA Extraction Efficiency and Genetic Profile Quality

As forensic DNA analysis has experienced countless advances in the past several decades, it has gained considerable notoriety among the general public, including those that are involved in the commission of crimes, leading to biological evidence that has been contaminated with various cleaning products in an attempt to conceal or destroy DNA evidence. This research examined the effects that three types of cleaning agents have on the ability of the Applied Biosystems® Automate Express™ Forensic DNA Extraction System to efficiently extract high quality DNA free from inhibiting compounds using the Prepfiler Express™ Forensic DNA Extraction Kit. This study further assessed the impact that these chemicals have on the entire forensic DNA analysis process through evaluation of the quality of genetic profiles using a quantitative scale. A dilution series (neat to 1:1000) was prepared from whole human blood, as well as from a bleach product containing sodium hydroxide, a quaternary ammonium-based multi-surface cleaner, and a carpet cleaner with hydrogen peroxide as the active ingredient. Each blood dilution was combined with each dilution of the three cleaning products and each of those samples was analyzed in triplicate. The amount of DNA extracted from bleach-treated samples was reduced compared to corresponding control samples due to destruction of the DNA prior to extraction. The quantification results from samples treated with both the ammonium-based cleaner and the hydrogen peroxide carpet cleaner were similar to controls. The automated system successfully removed inhibitory compounds from samples containing sodium hydroxide and quaternary ammonium compounds, but the blood samples containing the concentrated hydrogen peroxide cleaner showed increased inhibition. The genetic profile quality scores indicated that the ammonium-based cleaner had no effect on profiles regardless of the dilution ratio of the sample, while samples containing at least equal amounts of bleach and blood can be expected to have complete dropout of all alleles. The inhibition previously mentioned due to the hydrogen peroxide carpet cleaner completely inhibited amplification in samples containing 1:100 or 1:1000 diluted blood treated with neat carpet cleaner. These results indicate that crime scene personnel should document any cleaning agents that may have contaminated biological evidence as it could significantly impact the results of DNA analysis depending on the type of product and its concentration in relation to the evidence.

Posted on April 16, 2019 by Dr. Mark McCoy
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