Legal Studies Commons^™

Determination Of The Trace Elemental Signature Of Drywall Dust And Its Implication As Forensic Evidence, Emilee Holmes

Master of Science in Forensic Science Directed Research Projects

Drywall is found in most homes built in the United States of America because it is cost effective, light weight, and easy to install. Its brittle nature makes it less resistant to impact which can cause dust to form if a force is exerted on it. Airborne dust can settle on anything or anyone around it and can be considered trace evidence for its ability to connect suspects, victims, and scenes; however, this type of dust is not emphasized as trace evidence and is not always collected due to a lack of understanding of their forensic signatures.The seven producers of …

Evaluation Of Direct-To-Amplification Cell Lysis Techniques For Forensically Relevant Non-Sperm Cells, Rhea Arya

Master of Science in Forensic Science Directed Research Projects

While efforts have been made to reduce the pervasive backlog of sexual assault evidence collection kits, the actual laboratory process remains very time-consuming due to the requirement of a differential lysis step before DNA purification, as well as intricate mixture analysis towards the end of the DNA workflow. Previous work in the Dawson Green laboratory at VCU has developed alternative solutions for differential extractions with sexual assault samples using both an in-tube and microdevice assay. Prior work led to the identification of an alternative sperm lysis method – alkaline lysis using 1M NaOH. However, the current lysis method used for …

Optimization Of Microfluidic Device Methodology For Optical Trapping Epithelial Cells In A Mixture, Brittney N. Hackworth

Master of Science in Forensic Science Directed Research Projects

Evidence containing biological mixtures can make DNA interpretation more difficult due to ambiguous allele calls and artifacts that may be present within electropherograms. Separating out these cell mixtures can be advantageous to the analysts’ analysis methods for identifying STR profiles with higher accuracy. A potential cell separation method that could be implemented in the beginning of the forensic DNA workflow is optical trapping.

This research utilized a 5W ytterbium linearly polarized laser split into two optical traps, paired with a microfluidic device to isolate spermatozoa and vaginal epithelial cells from a 1:1 mixture of vaginal fluid and 1:20 diluted seminal …

Analysis Of Forensic Relevant Cell Mixtures Using Cellular Autofluorescence And Fluorescence Activated Cell Sorting (Facs), Shayla Smith

Master of Science in Forensic Science Directed Research Projects

Biological mixtures containing DNA from more than one contributor can make DNA profile interpretation challenging, especially for ‘touch’ or trace biological evidence. One approach to improve this is by differentiating cell populations from separate individuals prior to DNA profiling by utilizing intrinsic features of cells such as size, shape, and biochemical profiles. The goal of this study was to develop a new method for detecting and separating contributor populations in biological mixture samples using flow cytometry, a rapid and non-destructive approach with an unexplored potential for forensic casework. To accomplish this, two different mixture systems were investigated (1) mixtures containing …

Investigation Into The Relationship Between Dna Content And Dna Yield Prediction And Presence Of A Multiple Contributor Cell Population In Trace Dna, Sarah Holton Roisch

Master of Science in Forensic Science Directed Research Projects

Due to advancements in DNA analysis technology and an increased ability to detect trace quantities of low template DNA, ‘touch’ or trace DNA has become a prevalent form of evidence for forensic investigations. Trace DNA is biological material left on a surface from skin cells after being touched or handled. The success rate of casework could be improved with new methods to non-destructively screen trace DNA to predict DNA yield and whether multiple cell populations are present in the evidence prior to STR analysis. Current methods of trace DNA analysis require quantifying the sample with qPCR followed by STR analysis, …

Horizontal And Vertical Transmission Of Microbes Associated With Blow Flies Of Forensic Importance, Gabrielle Alisa Burton

Master of Science in Forensic Science Directed Research Projects

Entomological and microbiological evidence can be used in the estimation of postmortem intervals (PMI). This study observes the horizontal and vertical transmission of the microbial community associated with blow flies of forensic importance. Variable region four (V4) of the 16S ribosomal DNA (16S rDNA) was amplified and sequenced from various life stages of blow flies (n=72) using dual-index high throughput sequencing strategy on the MiSeq FGx platform. No significant difference in bacterial community structure was observed between blowfly adults with carrion access and blowfly adults with no carrion access. Dysgonomonas, unclassified Proteobacteria, Escherichia, Ignatzschia, Providencia, …

Morphological And Autofluorescence Signatures For The Identification Of Vaginal Cells In Mixture Samples Containing Saliva And/Or Epidermal Cells, Hannah L. Burden

Master of Science in Forensic Science Directed Research Projects

In forensic casework the identification of body fluids at a crime scene can frequently play an important role in reconstructing the events that occurred. There are several bodily fluid identification methods to characterize unknown stains recovered as evidence. However, there has not been a reliable method for detecting the presence vaginal cells and/or differentiate it from other forensically relevant tissue types that may be recovered from a crime scene. The detection of vaginal fluid is important for forensic casework due to the abundance of sexual assault kits that are not only backlogged but continue to be submitted to the lab …

Comparison Of Cell Counts To Dna Yield In Mock Biological Evidence Samples, Jacob Sewell

Master of Science in Forensic Science Directed Research Projects

The implementation of rapid DNA analysis systems is of interest to forensic DNA casework, as this technology exhibits a sample-to-profile time of approximately two hours with limited handling of samples. This decreases the likelihood of contamination, and can potentially reduce DNA backlogs; however, current rapid DNA analysis systems do not execute one crucial step of the forensic DNA analysis workflow: human DNA quantitation. This step is necessary for DNA profiles to be compliant with the FBI’s Quality Assurance Standard 9.4, allowing DNA profiles to be uploaded and searched within the CODIS database. Coupling traditional qPCR methods with rapid DNA analysis …

Development And Validation Of Microrna Markers For Forensic Body Fluid Identification Using Rt-Qpcr, Jane Goble

Master of Science in Forensic Science Directed Research Projects

Body fluid identification is one of the first and most fundamental steps in the forensic DNA workflow. It allows analysts to determine where a sample might exist on an item of evidence, as well as the type of sample that they are dealing with. However, current serological methods have been documented to produce false or inaccurate results in some cases, and may consume large amounts of sample during processing. Molecular methods, such as the use of microRNA and microbial profiles have been introduced as a means to increase specificity of testing, and have even been combined into a singular assay …

Evaluation Of Cytokeratin-Specific Antibody And Autofluorescent Signals As Predictors Of Time Since Deposition For Saliva Samples, Dillon Ryder

Master of Science in Forensic Science Directed Research Projects

In a forensic investigation, STR profiles generated from biological evidence can frequently be informative to identify an individual or provide an investigative lead. However, STR typing does not provide information to answer activity-level questions which can be highly important to a criminal case, such as the Time Since Deposition (TSD) of biological evidence. Determining the relative time in which a biological sample was left at a crime scene would provide additional information regarding the timeline of a crime and a person of interest’s relationship to the scene. One proposed method of estimating TSD is to use flow cytometry to analyze …

Assessment Of The Acidified Hydrogen Peroxide Method On Uncontrolled Fired Cartridge Case Samples, Kylie S. Richardson

Master of Science in Forensic Science Directed Research Projects

The use of fingerprints to identify individuals in forensic cases has been useful for many years due to the persistence and individuality of the prints. In addition, the presence of firearms in forensic casework is steadily increasing over the years. This study aims to expand upon prior research in the development and recovery of latent prints on fired, brass ammunition using an acidified hydrogen peroxide method. Although latent prints are left on the cartridge casing of ammunition during the handling and loading of ammunition into the firearm, it is hypothesized that the pressure within the barrel of the firearm during …

Evaluation Of The Age Of Evidence In Mock Biological Touch Evidence Samples, Emma P. Hirst

Master of Science in Forensic Science Directed Research Projects

As more sensitive DNA profiling techniques have been developed, questions about how and when the DNA was deposited have become a driving issue in forensic casework. Image flow cytometry (IFC) offers a way to estimate the time since deposition (TSD) of trace DNA samples based on individual cells' morphological and autofluorescence properties. Previous work has shown that a TSD can be determined from a single contributor in touch samples. To determine if TSD could be correctly estimated for mixtures containing a fresh deposit (less than a week old) and an older deposit, this project characterized a series of samples that …