Forensic Science Institute

Tag: research – Page 2

Research: A Validation of Promegs’s PowerPlex 16 HS System Testing the Strengths and Limitations

An internal validation study was conducted using the PowerPlex® 16 HS system to ensure proper performance on the Applied Biosystems 3130 Genetic Analyzer in the University of Central Oklahoma laboratory. Manual extraction with the DNA IQ^TM system was performed. The Quantifiler^TM Human Quantification kit was used to quantify the samples. Promega Corporation’s PowerPlex® 16 HS system was used to amplify DNA samples on a GeneAmp® PCR System 9700 thermal cycler. Separation occurred through capillary electrophoresis on an Applied Biosystems 3130 Genetic Analyzer. Following parameters established through the validation, an environmental study was conducted to simulate casework samples. The environmental study included ultraviolet treatment, tannic acid, humic acid, and hematin. The results support the multiplexing system is capable of handling DNA samples.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: External Validation of Consecutive Matching Striae Technology

Firearm and tool mark identification relies on criteria that have been accepted in the field to assist firearm examiners in determining if a bullet is fired from a particular firearm. In this research, criteria for firearm conclusions were reviewed, in light of current challenges by the scientific and legal community, concerning the reliability of firearm and tool mark identification theories. The aim of the research is to determine the effectiveness of Consecutive Matching Striae (CMS) criteria with respect to two-dimensional and three-dimensional marks viewed on both known and unknown test bullets of different caliber weapons. This research was conducted using .25 Auto, .380 Auto, .38 SPL, 9mm, .40 S&W, .45 Auto, and 7.62×39mm bullets. All data were used to evaluate the validity of CMS for identification purposes by examining groove impressions. The results revealed that current CMS criteria were valid for firearm identification but some known match comparisons were excluded. Therefore, new proposed criteria were demonstrated for assistance of firearm identification.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Validation of Enzyme-linked Immunosorbent Assays for the Detection of Licit and Illicit Drugs in Human Breast Milk

There are many instances when mothers are unable to provide their own milk, which is the case with many prematurely born infants. Breast milk banks and facilities that process human milk provide an alternative solution to synthetic or animal derived infant formula, allowing babies to receive the benefits of human breast milk. There are many drugs that can pass into a woman’s breast milk and cause possible harm to an infant. It is important that donor milk be screened for drugs-of-abuse in order to prevent this from occurring. The purpose of this study was to optimize and validate enzyme-linked immunosorbent assays (ELISA) for the detection of a seven-drug panel in human breast milk. The following Neogen Corporation kits were utilized: Amphetamine Ultra, Benzodiazepine Group, Cocaine/Benzoylecgonine (BZE), Cotinine, Opiate Group, Oxycodone/Oxymorphone, and THC. Sample dilutions that minimized breast milk matrix interference were determined, and cutoff levels for each assay were proposed based on the linear range of the assay. The seven-drug panel was validated through the assessment of drift, precision, and accuracy. The Cocaine/BZE and Opiate Group cutoffs were increased from 30 to 50 ng/mL after several false negative results were obtained during the accuracy portion of the validation. The ELISA assays were validated at two different sites, and the robustness of the method was demonstrated.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Emerging Infectious Disease: Ecological Niche Model and Molecular Identification of Angiostrongylus cantonensis in Rodents from Oklahoma and Louisiana

Emerging infectious diseases (EIDs) have devastating effects on wildlife. Angiostrongylus cantonensis is a zoonotic EID that causes eosinophilic meningitis in humans and neurological illnesses in wildlife. Because A. cantonensis has been documented worldwide and continues to spread, it is a clear example of an EID of potential pathogenicity to both humans and wildlife. The advent of modeling techniques to predict the geographic distribution of pathogens, in conjunction with modern molecular genetics, provides a unique opportunity to gain insight into the distribution of A. cantonensis, and evaluate methods of disease surveillance. I used the modeling program Maxent in combination with IPCC bioclimatic variables to build an ENM to predict current and future distributions of A. cantonensis. I tested these predictions by sampling rodents in SE Oklahoma and Louisiana and analyzing tissues for the parasite using qPCR. Out of 34 samples identified as positive, sequencing analysis revealed only three definitive identifications, one from Sigmodon hispidus and two from Rattus norvegicus. The remaining 31 samples were classified as “false positives” by qPCR. Sequences from positive samples were compared to those on GenBank through BLAST with a match to A. cantonensis. Phylogenetic analysis confirmed relationships by comparing positive sample sequences to A. cantonensisand two closely related species, Angiostrongylus vasorum and Angiostrongylus costaricensis. All phylogenetic methods grouped positive samples and A. cantonensis with 100% confidence. The projected future distribution for A. cantonensis indicates an overall decrease in suitable habitat and range shift. The findings from this study alter our current perspective of A. cantonensis within the United States, and demonstrate the successful application of two important epidemiological techniques that may be applied more broadly to a variety of EIDs.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Investigating the XBOX 360 with Kinect: Implications for Digital Forensics

The Microsoft Xbox 360 with Kinect is the latest online gaming device on the market. The addition of the Kinect gives the Xbox 360 the ability to control games without using a controller, to record voices and to snap digital images of the users. The Xbox 360 is recognized as a popular entertainment and educational device, as well as a platform that can be used by online predators to victimize children or store evidence of criminal activity. Because the Xbox 360 can be used in criminal activity, it is vital that digital forensics examiners be able to recover items of evidentiary value. While some research has been conducted on forensic examination of the Xbox 360, no studies have addressed the evidence left on the Xbox 360 with Kinect. This study examines the evidentiary artifacts left by users on the Xbox 360 with Kinect and the implications for digital forensics examiners.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Evaluation of Familial Search Software for Forensic Investigation using Mutation Rate Adjusted Synthetic Data Sets

The use of a national DNA database, such as CODIS (Combined DNA Index System), to provide leads in unidentified missing persons and violent crime cases can be an advantageous tool for investigators nationwide. When a search of such a database yields no “hit,” investigators are not necessarily left with a dead end. Familial searching of DNA databases uses specialized software to examine the database for possible relatives of the individual who contributed to a questioned DNA profile obtained at a crime scene by searching the genetic information of the convicted offenders already in the database. A list of likelihood ratios are ranked and compiled in order to predict the possible biological relationship of the questioned profile and the resulting partial matches from the database. The focus of this research will be concentrated on how known microsatellite mutation rates at the CODIS core loci affect the familial search software’s ability to return the correct familial relationships. The researchers will evaluate variables associated with mutation rates in STR, Y-STR (Y-chromosome DNA) and/or mtDNA (mitochondrial DNA) markers in software. To do this, the researchers will be generating synthetic families to test kinship and sibship analysis while manipulating the mutation rates within the software to reflect those, which are now published. Practical considerations such as success rate, false positives rates, false negatives rates, cost of analysis and time will be thoroughly evaluated. Socio-ethical issues will also be explored involving the legality issues of states permitting familial searching with the current software validation capabilities.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Comparison of Extraction Kits PrepFiler and DNA IQ for STR Analysis of Contact DNA Samples

Contact DNA evidence is becoming a common occurrence at crime scenes and is often collected and analyzed for human identification. Current Short Tandem Repeats (STRs) techniques are still limited in Low Copy Number (LCN) DNA analysis due to contamination and stochastic effect. Increasing DNA yield from the extraction step is a potential benefit for many investigations. One hundred and fifty samples collected from five female individuals on five commonly-used items were extracted by two forensic extraction systems: DNA IQTM and PrepFiler Kit® with subsequent genotyping by PowerPlex® 16 HS system. Results determined that these extraction systems are not suitable for LCN DNA samples. Only two complete STR profiles were produced without contamination. These findings indicated that further improvements are required in order to utilize STR analysis for LCN DNA.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Use of Digital Forensics Corpora in the Validation of Data Carving Function

The need for an improved validation and verification paradigm in digital forensics is becoming apparent. The current system often results in digital forensics tools being used that have never been tested in reality (Beckett & Slay, 2007). Several articles (Beckett & Slay, 2007; Garfinkel, 2007; Garfinkel, Farrell, Roussev, & Dinolt, 2009) suggest that the use of standardized data sets, or corpora, may be the key to developing a better validation and verification protocol. This paper outlines a study that will utilize digital forensics corpora to validate the carving function of Access Data’s Forensic Tool Kit. Does FTK’s data carving function perform as intended and recover all possible data? What is the error rate of FTK’s data carving function? Does the use of digital forensic corpora provide accurate and reproducible validation results? Is the use of digital forensic corpora a viable validation method for practitioners to use in their own labs? The proposed study will not only evaluate the use of digital forensics corpora in the validation and verification process, but will also serve as a validation study of the FTK’s carving function, complete with error rates.

Posted on April 16, 2019 by Dr. Mark McCoy

Research: Learning Strategies of Digital Forensics Examiners and Students Studying Digital Forensics

Digital Forensics, also known as Computer Forensics, is the investigation of any digital media in order to find evidence. This media can include computer hard drives, flash drives, cell phones, etc… This discipline is relatively new compared to the other forensic disciplines, and is evolving at an exponential rate to keep up with changing technology. Digital forensics investigators often come from different backgrounds. Some have computer science backgrounds and are trained to be investigators while others come from the investigator side and are trained in computer forensics. Some examiners do not have a background in either area, but are being trained in both. There have been many studies concerning the learning strategies of adults. However, no studies have been done to find a common learning strategy among this group. This study determined the predominant learning strategy of a convenience sample of this diverse group to be Problem Solvers using the Assessing The Learning Strategies of AdultS (ATLAS) tool. This allows educators in this field to have a better understanding of how these students learn, and make the process more meaningful. Also, the educators of the on-going training in digital forensics will be more successful in presenting new material to experienced investigators already in the field.

Posted on April 16, 2019 by Dr. Mark McCoy

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