Forensic Science Graduate Research Projects
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Item A Comparative Analysis of Casting Materials on Developed Latent Prints(2020) Brock, Jenny F.The drive to preserve and collect latent prints has led to the creation of innovative products and technologies. However, because of the increasing variety of the implements, supplementary research was necessary to ensure appropriate application of these products dependent on circumstances, environments, and availability. Further, crime scene technicians and departments, who rely on experience and accessibility of materials, also need current information on product capabilities and limitations. This research compared AccuTrans, First Contact polymer solution, and Elmer’s glue as casting materials applied to latent prints developed with dual-use black powder. The latent prints samples (n=60) were deposited on either flat or curved substrates, and then preserved with one of the three casting materials. Evaluation of the collected latent prints included: whether friction ridge detail was present, how many individual characteristics could be observed with a restriction of 10, and how many levels of friction ridge detail were represented. The results of this study indicated that no matter which casting material was selected, there was no significant variation in the ability of the materials to perform (p=.794) and successfully collect a developed latent print for examination on certain substrates (p=.462). Individually the casting materials had observable strengths and weaknesses such as short or extended dry times, deformation after collection, and ease of collection.Publication A Comparative Evaluation of Kits for Seminal Fluid Detection(2024-05) Sperling, Anaya; Knight, KellySeminal fluid detection kits are commonly used within the forensic science field to determine whether an unknown sample contains semen. The ability to correctly identify seminal fluid in any criminal cases involving bodily fluids is of the utmost importance. The ABACard p30 kit is most commonly used in forensic DNA laboratories to detect semen. This study “A Comparative Evaluation of Kits for Seminal Fluid Detection” will compare the ABACard p30, RSID - Semen, and SERATEC Semiquant PSA kit to the Bluestar Identi-PSA kit which is newer to the field. Bluestar, ABA, and SERATEC kits test for the presence of prostate specific antigen (PSA) which is the protein present in semen. On the other hand, RSID - Semen detection kit tests for semenogelin which is the protein that is found in ejaculated semen and is responsible for sperm immobilization in the seminal coagulum. To evaluate the specificity of these kits, breastmilk, saliva, and blood will also be tested in duplicate. Labor intensity, cost, and sensitivity will also all be compared between the four kits. Sensitivity will be evaluated by testing a series of dilutions of semen in duplicate from 1:10 to 1:100,000. It is expected that all four kits will be equally effective (creating true positives) in detecting semen, however, there will be differences in labor intensity and cost. It is also anticipated that a potential false positive with the breastmilk will happen since previous research has reported the detection of prostate specific antigen or semenogelin in breastmilk. The result of a positive test from breastmilk would pose the question of whether said kit would be deemed to be as reliable as stated. It is expected to conclude that between the four kits: Bluestar Identi-PSA, ABACard p30, RSID - Semen and SERATEC Semiquant PSA, each will yield different results when it comes to specificity and sensitivity.Item A Quantitative Study On Extraction Versus Direct Amplification Of Touch DNA Samples(2022-05) Basrawi, JudeTouch DNA, also known as Trace DNA, is an important aspect of criminal investigations, as the perpetrator is unaware of the DNA they have left behind. While there are multiple ways to extract touch DNA, it has been established that direct amplification provides exemplary results. Direct Amplification is the process of analyzing the samples by amplifying them without extraction or quantitation. However, there is no measure on how much information direct amplification provides as opposed to other widely used methods including standard extraction procedures. This study aimed to look at the differences in information obtained when processing a touch DNA sample using standard extraction procedures versus a direct amplification approach. Understanding the scope of information collected by direct amplification versus standard extraction procedures can be used to facilitate new protocols for processing touch DNA. This study focused on collecting touch DNA samples from 20 volunteers and processing the DNA using two methods. In the first half of the study, half of the samples were extracted, quantified, and amplified using the InnoXtractTM, InnoQuantTM and InnoTyperTM kits, respectively, from InnoGenomics, LLC. The next part of the study included adding swabs to be directly amplified using the InnoTyperTM 21 kit. Rather than the standard extraction protocol, this method included placing the swab heads directly into the PCR tubes for amplification. Samples undergoing direct amplification are expected to show more information due to the fact that standard extraction protocols often result in loss of DNA. Data generated from capillary electrophoresis was compared by reviewing the allele peak heights. Samples exhibiting “real” and representative peaks were further reviewed to determine if the peaks were real or due to artifacts such as noise. The research findings may lead to revised protocols that can be applied to difficult sample types, such as touch DNA, which often result in partial DNA profiles that often contain very little information.Item Age-at-death estimations using cementochronology in thermally altered teeth(2021-04) Weaver, Ryen L.Macroscopic age-at-death estimations provide age ranges that give broad and often insufficient insight to an individual’s chronological age. Accurate age estimations can become more complex for a forensic anthropologist if the unknown individual has been subjected to extreme heat from an assortment of scenarios that include but are not limited to structure fires, airplane crashes, automobile accidents, and attempts to conceal evidence of homicide. Due to their high mineral content and sequestered placement in the jaw, teeth have the ability to be one of the best-preserved human tissue remains in extreme heat situations (Beach, Passalacqua, & Chapman, 2015). Cementochronology utilizes the cementum, the mineralized covering of a tooth root, as an aid in estimating an individual’s age (Colard, et al., 2015). The utilization of cementochronology is one of the most accurate ways to estimate age-at-death due to the countable cementum annulations found in the cross-sections directly correlating to the individuals age (Wittwer-Backofen, 2004). This study aims to provide an in-depth analysis of thermal alteration to human teeth by various accelerants when utilizing the cementochronology method to build a biological profile. The sample in this study consists of 36 teeth from both male and female donors from all odontological positions ranging in age from 9-87 years. Three accelerants with varied volumes were used to determine if the readability of cementum annulations can still remain accurate after alteration. Results indicated that the type of tooth had significant impact on the ability to count annulations. Annulations were able to be read and estimated after alteration with all three accelerants used in this study. However, acetone yielded the lowest results with the most severe alterations. A novel formula was developed to help approximate the amount of cementum annulations found within each sample. This formula was found to yield estimated tooth cementum annulations that were highly correlated with the actual ages of the individuals from whom the samples were from. After thermal alteration of teeth with accelerants it was found that cementochronology is an accurate and helpful tool for estimating age-at-death in unknown individuals.Item Bullet Hole Characteristics, Limiting Factors, and Reconstructing Shooter Location within a Crime Scene(2020) Jennings, JonatthanShooting scene reconstruction and the identification of where the shooter and weapon most likely were located, can be critical pieces of information for law enforcement and crime scene investigators. During an extensive literature review, the gap which appeared was identifying the most likely position of the shooter when accounting for limiting factors, such as room size and furniture. There are several ways to conduct shooting trajectory analysis, with individuals such as Haag, L., and Haag, M. (2011), Hueske (2009), Gardner and Bevel (2009), Gardner and Krouskup (2019), writing at length about the process of determining shooting trajectory and overall crime scene reconstruction. The trajectory analysis for this project was adopted from Gardner and Bevel (2009) and through coordination with the Virginia State Police and included using trajectory rods, angle finders, protractors, and lasers to determine the trajectory of the bullet. Then limiting factors along the path of the bullet, gunshot residue (GSR), and overall room size was accounted for, to identify the most likely position of the shooter. According to Gardner and Bevel (2009) and through coordination with certified crime scene experts, it was determined that shooter positions are broadly assigned to zones one through three. The results expected from this project are to refine zone 1 described as the most probable shooting location, identify the overall accuracy rate of shooting trajectory analysis, and to develop a predictive model statistical analysis to determine the impact of the limiting factors on predicting the shooter’s distance. The conclusion anticipated from this research is when all factors are taken into account, a most likely shooter location could be identified within +- three through five feet.Publication Comparison of Commercial DNA Extraction Kits for Extraction of DNA From Bones Prepared Using the Novel Theralin Method(2023-11-06) Bowers, Madalyn; Wilson, MarkThe extraction of DNA from bones to produce high quality samples is extremely important in cases involving unidentified human remains and victims of mass disasters, and many times in these cases, only human bone is available as a source of DNA that can be used to identify the individual. A novel method of preparing bones for extraction using TheralinTM, a precipitating fixative that demineralizes bone, has been developed by researchers at George Mason University. This novel method essentially transforms the bone into a gum-like state that allows for the bone material to be cut into smaller pieces and then digested using lysis buffers. Research has not yet been performed to determine an ideal method of DNA extraction from Theralin-prepared bone, and this study seeks to answer that question. In this study, four different methods of DNA extraction using commercial extraction kits were carried out on bone samples that were prepared using the Theralin method. These extraction methods were the Qiagen QIAamp® DNA Investigator kit protocol with MinElute columns, the PrepFilerTM BTA Forensic DNA Extraction kit protocol with PrepFiler magnetic beads, a combination method using the Qiagen lysis buffers with the PrepFiler magnetic beads, and a combination method using the PrepFiler BTA lysis buffers with the Qiagen MinElute columns. Following extraction with these four methods, the DNA extracts were quantified using the QuantifilerTM Trio DNA Quant kit, and the quantification values of the extracts were compared to determine which method provided the highest amount of DNA. The extracts were amplified using the GlobalFilerTM PCR Amplification kit and genotyped using the Applied Biosystems 3500 Genetic Analyzer with GeneMapperTM ID-X v1.6 software. The STR profiles were compared to the known profiles of the bone samples and analyzed for allelic dropout and signal strength metrics to determine the quality of each DNA extract. The results of this study provided insight into the usefulness and efficiency of the Theralin method of bone preparation, combined with a commercially available DNA extraction technique, to give quality DNA extracts that can be used for downstream applications.Item Comparison of Forensically Significant Carrion Insects at Buried vs. Surface Remains in Northern Virginia(2023-11-20) Kline, Sonja K.; DiZinno, JosephSeveral factors complicate using necrophagous and other forensically important insects to determine a post-mortem interval in death investigations. First, insects demonstrate wide temporal ranges and spatial diversity, making it difficult to predict which species will be present. Secondly, carrion insects have consistent patterns in carcass size preference, and such patterns may indicate that dismembered remains, which represent smaller food sources, have different patterns of succession than those documented for whole cadavers. Although carrion insect succession has been well documented on whole human and porcine remains, there is limited documentation of insect succession for sectioned, or dismembered, remains. This study compares data collected from dismembered porcine remains in Central Virginia to published data for whole cadavers. Additionally, data was collected from surface-deposited dismembered and from buried remains to address differences between whole and dismembered remains under both types of conditions. Results of my study suggest that while fauna on surface dismembered remains followed a consistent successional pattern, the insects present were typical of later stages of decomposition on whole bodies. Surface dismembered remains also showed higher abundances of different Diptera taxa, such as Heleomyzidae, Sepsidae, and Phoridae, compared to the most common families – Calliphoridae, Muscidae, and Sarcophagidae – traditionally reported for whole remains. Additionally, the final amounts of tissue remaining were similar for both surface-deposited and buried dismembered remains, suggesting that smaller body parts may decompose equally rapidly regardless of the level of activity of insects or the diversity of arthropod fauna. Finally, fauna on buried remains consisted of understudied taxa that recent studies show have species-specific food preferences, and therefore, that might be of forensic significance, such as Collembola, Mycetophilidae, and Acariformes mites.Item Comparison of two different photo protocols and increasing the accuracy of 3D modeling of snow shoeprints by Photogrammetry(2021-03-29) Sheen Vento, KarlaSometimes a shoeprint can help in narrowing down the number of suspects in a crime scene, so having an efficient recovery method for them can be helpful (Andalo et al., 2012). Photogrammetry has been proposed as a simple and reliable method for shoeprint analysis in previous studies, however, its use in certain surfaces such as snow can be challenging, and it also requires following a strict protocol for picture taking (Larsen and col., 2020). The objectives of this study are to test the equivalency of an alternative picture-taking protocol proposed by Larsen et al. with the standard protocol proposed by the developers of Digtrace, a software that allows the 3D modeling of shoeprints; and to test the effectiveness of different techniques for improving the quality of shoeprint’s photos taken in snow. In the first experiment, two shoeprints were created on sand and mud, and photographed using Larsen’s and Digtrace’s photo taking protocol. A series of 3D models were created in Digtrace, randomized, and cloud points extracted from them were compared using the CloudCompare software to assess differences in variability. In the second experiment five shoeprints were created in snow and several enhancing techniques (oblique light, red filter /black – white photo, red, and blue dyes) were used to increase the contrast of the photographs. The same comparison process from experiment was used to determine a reduction in the variability of cloud point distances with a control group. The results shown a higher accuracy from Larsen’s protocol (mean distance 0.1025 mm) than Digtrace’s protocol on mud surface, however on sand surface Digtrace’s protocol revealed less error distance (0.0968 mm) than Larsen’s protocol. The results from the second experiment shown that the use of blue and red dyes produced noticeable improvement of the reliability values. (mean error distance 0.0648 mm and 0.0734 mm). In contrast, oblique lights and red filters/black-white photos did not produce a significant improvement. This study shows that both Larsen’s and Digtrace’s protocols can be used to build reliable shoeprint 3D models and that the accuracy of 3D snow shoeprints can be improved with a simple method such as the spraying of red or blue dyes.Item Comparison of Vacuum Metal Deposition and Gun Bluing for Developing Latent Fingerprints on Fired Nickel-Plate Brass Ammunition(2020) Osborne, AmyVacuum metal deposition (VMD) is a highly sensitive method for developing latent fingerprints on semiporous and nonporous surfaces with extensive research focusing on various classes of polymers. The relatively high cost of a VMD unit and the need for an experienced operator, has prevented the technique from replacing traditional methods, such as gun bluing, for developing latent fingerprints on spent cartridge casings. A literature review revealed that while VMD has the potential to be a powerful technique in the development of expended cartridge casings, there is a lack of comparison studies between VMD and other latent print development techniques on shell casings. The purpose of this study was to determine if there is a significant difference in the equality of latent fingerprints developed by vacuum metal deposition and gun bluing (GB) on fired cartridge casings. To accomplish this, a single latent print spiked using a sebaceous oil reference pad was deposited on 250 9mm nickel-plated brass ammunition samples and developed by either VMD or GB. From these 250 casings, 50 were treated in a brief preliminary study that subsequently guided the gun bluing process. As a result, a modified gun bluing protocol using a 20% Brass Black (Birchwood Casey, Texas, USA) solution was followed to process 100 casings while the remaining 100 were subjected to silver/zinc deposition in the VMD560 (West Technology Forensics, England, UK). All casings were photographed, examined, and graded on a 0-4 scale by a Certified Latent Print Examiner. Of the 200 casings developed, 115 samples failed to yield any ridge details (Grade 0) with 54.78% having been developed by VMD. There was limited ridge detail (Grade 1) present on 62 samples with comparable results from both techniques. Low quality detail (Grade 2) was visualized in 23 samples with 86.96% having been produced by GB. Using the Kruskal-Wallis H test with a 90% confidence level to determine statistical significance, the primary hypothesis that VMD would be the superior method was not supported. Therefore, it is recommended that nickel-plated brass casings be processed using the modified GB protocol.Item Computed Tomography as a Supplement for Analyzing Antemortem and Perimortem Blunt Force Cranial Trauma(2019) Marks, FeliciaWithin the field of forensic anthropology, skeletal trauma analysis plays a critical role in reconstructing the events surrounding the life and death of an individual. For example, analyzing cranial blunt force trauma (BFT) could provide insight into a history of abuse based on the amount of healing present. Blunt force trauma to the skull has been researched extensively in the past, but to date has not focused on interpreting the timing of fractures to differentiate early antemortem from perimortem stages of healing. The goal of this research was to examine the fracture characteristics present by traditional macroscopic assessment, then enhancing the details of cranial injuries through computed tomography (CT) in order to have better visualization and aid in determining the timing of fractures. A total of 23 antemortem and 20 perimortem BFT injuries were initially observed within a sample of 30 skulls from skeletal collections at the Smithsonian’s Museum Support Center and National Museum of Natural History. The skeletal collections consisted of the Robert J. Terry Anatomical Collection, and the Peruvian skeletal collection created by Aleš Hrdlička in the early 1900s. This study revealed that by using computed tomography for analyzing cranial blunt force trauma, there was no significant difference in the further classification of fracture timing for early antemortem and perimortem defects.Item Crime Scene Documentation- iPhone vs the Nikon D5600(2021-05) Mansell, AndrewA picture is worth a thousand words because of its power and influence. They are an unbiased representation of fact and why crime scenes are documented with powerful cameras like the Nikon Digital Single-Lens Reflex. Modern smartphone technology provides us with an alternative. This study compares an iPhone XS Max to a Nikon D5600 to accurately depict a crime scene. This study compares each camera's mechanisms and judges the quality of their exposures through sharpness, resolution, and acutanceItem Deconvolution of DNA Mixtures Using Replicate Sampling and TrueAllele® Mixture Interpretation(2020) Antillon, SaraAnalysis of DNA mixture evidence does not always yield distinct profiles. This process is further complicated with low template DNA (LT-DNA)samples often seen in forensic casework. Traditional qualitative methods use thresholds to distinguish allele peaks from stutter peaks, noise, etc.resulting in data being omitted during analysis. In cases where LT-DNA is present, low peaks that could potentially be attributed to low contributor profiles may not be called due to these instituted thresholds. The probabilistic genotyping computer software program created by Cybergenetics (Pittsburgh, PA), TrueAllele® Casework, considers all data and performs quantitative analysis using probability to represent uncertainty. It objectively forms likelihood ratios (LR) that compare the probabilities of an evidentiary genotype with a suspect genotype relative to a reference population. A joint likelihood function (JLF) takes two or more independent sets of data and compares them jointly as opposed to a single event. The JLFcan elicit more identification information proving useful in DNA mixture analysis. This project used TrueAllele® Casework to perform DNA mixture analysis on two sets of previously published mixture data provided by Cybergenetics. The first set comprised 40 two contributor mixture samples and the second set included four sets of 10 randomized mixtures with two, three, four, and five contributors, respectively. The selected samples were interpreted singly and jointly in three variable groups: mixture weight, template concentration, and complex mixtures. The differences between the match logLRs of the single and joint analyses were calculated and an information gain was seen in all three groups when the samples were analyzed jointly. Changing DNA collection and amplification procedures for touch andDNA mixture evidence samples will increase the amount of data available forDNA mixture analysis using probabilistic genotyping. These procedures can be modified so that multiple swabs and replicate amplifications produce more data that TrueAllele can analyze using the JLF. Jointly analyzing each independent evidence data can lead to higher match statistics which will ultimately help in the identification of those who commit crimes.Item Deep Brain Stimulation: Treatment for Clinical Depression(2020) Admassu, AzariaDepression is the most common mental disorder in the United States. A person with this disorder is generally described as feeling sad, discouraged and in general, disinterested in life. Deep brain stimulation (DBS) is a method of electrically stimulating a specific part of a brain using implanted electrodes. Since the symptoms of major depressive disorder have been linked to the dysfunction of the reward circuitry system of which the NAcs are the major players of, DBS to these neurons have been one suggested method to improve patients’ symptoms. In 2013, DBS of the NAcs had given a promising result when patients treated by DBS had shown an improvement with little to no side effect. This paper will discuss the advantages to DBS as an anti-depressant by the assessment of available studies and will further discuss the current as well as future challenges facing DBS.Item Degrees of contrast: Detection of latent bloodstains on fabric using ALS and the effects of washing(2020) James, Matthew E.Bloodstains are a useful piece of evidence for solving many crimes. The DNA analysis of bloodstains deposited on a piece of clothing can identify whose blood is on the clothing and may place a subject at the scene. In some cases, the stain’s shape, and overall pattern, can provide much more information. However, it is particularly difficult to identify bloodstains on dark clothing and clothing with patterns. Current methods to detect these stains include advanced photography techniques with Alternate Light Sources (ALS) or the use of chemicals that react to the hemoglobin and fluoresce. Photography methods are non-invasive, but there is little research on what wavelengths are the most effective. Chemicals such as Luminol, Bluestar, and Fluorescein are effective, but ultimately ruin the pattern and prevent morphology interpretation of the stain. This study explores the use of ALS to photograph bloodstains in order to provide an alternative non-invasive tool before the use of chemical detection techniques. This study examined whether blood always absorbed light in the 300nm to 900nm range and the best wavelength for observing blood on dark and or patterned fabrics. It also explored whether fabric type, fabric color, or pattern affected the ability to view blood on fabrics, if washing the fabric affected the use of ALS, and, if so, to what extent. Sixty-nine fabrics were photographed in monochrome under ambient light, and then with and without filter under 350nm - 380nm (UV), 400nm - 430nm (Violet), 430nm - 480nm (Blue), 480nm - 560nm (Green), and 800nm - 900nm (Infrared) light. Each photograph was bracketed to ensure the best exposure and contrast between the stain and fabric. In total, 33 photographs were taken for each fabric after each wash cycle. Contrast was measured between the bloodstain and the fabric using ImageJ software to measure the effectiveness of each wavelength. Results indicated photography with ALS was a viable method for blood detection on fabrics and should be used prior to chemical means. Further, infrared, followed by violet light with no filter, were the most effective light sources for viewing bloodstains on dark fabrics without the use of chemicals.Item Direct Transfer: Obtaining Latent Prints from the Skin of a Living Person(2021-05-10) Hinze, DustinFingerprint identification has been at the core of Forensic Science for more than 100 years. It remains one of the most valuable tools to assist law enforcement in identifying suspects and solving crimes. Over time techniques have made it possible to recover latent prints from the skin of human remains and, in some cases, a living person’s skin. Identifying latent prints from human skin could directly corroborate or refute statements or provide investigative leads. One technique is called direct transfer, in which paper is pressed against the skin to transfer latent prints present on the skin. The paper is then processed with various techniques to develop the potential latent prints. This study examined the direct transfer technique in obtaining latent prints deposited on the skin of a living person utilizing kromekote, thermal, and ink/laser jet paper. Magnetic powder and Indanedione were utilized to process each type of paper to develop the potentially transferred latent prints. This research consisted of 1,035 trials conducted at several time intervals: immediately after print deposit, 5, 10, 15, and 30 minutes after deposit. The purpose of this research was to identify the most effective transfer paper substrate, fingerprint development technique, and timeframe to recover latent prints from the skin. The substrate and development technique did not have a significant impact on the results; however, time of recovery after deposition had a significant impact. After five minutes, there was a drop in the level of identification which grew more significant over time.Item Enhancing Forensic Science Education for Law Enforcement Personnel(2022-05) Anderson, SydneyAs crime escalates throughout the United States, it is important that law enforcement personnel are aware of, and educated, in the vast array of forensic science disciplines that can, in many cases, aid in the identification of suspects. This research project aims to identify and examine the needs of the law enforcement community regarding forensic science education, with the goal of constructing easily accessible training programs and information repositories. Questionnaires to assess current knowledge and training, and to identify areas of need and improvement, were recently formulated and disseminated to law enforcement agencies across the United States. Forty-eight responses were received from officers/agents in 20 states. Thirty-eight respondents were invited to participate in focus groups, with 8 opting to participate in a final survey instead. An additional 23 individuals were excluded due to missing response fields or incorrect self-identification as a member of the law enforcement community. The survey focused on assessing the needs for future trainings as identified and articulated by Law Enforcement Personnel. Focus groups were conducted following the initial survey to learn in greater detail what training topics are the most valuable. Five focus group sessions were held with 2-4 attendants per session; each session lasted approximately one hour long. Exploratory methodology was employed in the focus groups conduct and design to gather information regarding the favored method of training, desired tools, and information dissemination techniques. Following the focus groups a final survey was distributed to the law enforcement community. 161 responses were received from officers/agents nationwide. 85 respondents answered all survey questions provided, 17 respondents answered some survey questions provided and 59 respondents answered zero questions. Training programs are planned in the near future with the goal of creating accessible educational training online, and/or in person, to all individuals involved in law enforcement.Item Estimation of Ancestry Using Mesiodistal, Buccolingual and Diagonal Tooth Measurements(2019) Navale, ShraddhaIn forensic science, when an individual is to be identified, inmost of the cases, teeth are considered the precious and reliable tool forobservation and analysis owing to the fact that they are the hardest tissueand the only last tissue to decompose in the body, they are multi-rooted onesakin the premolars and molars and also one single rooted tooth – thecanine, attributable to the fact that it has the longest root and thereforebetter allow for better anchorage. Keeping this in mind, this project aims atbeing able to estimate ancestry from the dental data collected viz: the crownmeasurements mesiodistally, buccolingually, diagonally and vertically such asthe crown height, namely. And in this research, it can be achieved byphysically measuring dental diagnostic casts using digital calipers and thenanalyzing the data generated from it using Discriminant Function Analysis.The interpretation and conclusion expected from this analysis is to be ableto classify the dimensions of the teeth as per their ancestral line.Item Evaluation Of Virtual Standard Curve Functionality Of The HID Real-Time Pcr Analysis Software By Comparison To Assay Specific Standard Curves And An External Standard Curve Generated In- House(2021-05) Mauriello, AngelinaQuantitative PCR (qPCR) plays a critical role in the field of forensic biology to determine the amount of “amplifiable” human specific DNA. If too much or too little DNA is present, it can result in profiles difficult to interpret. Therefore, qPCR is beneficial in determining the quality and quantity of DNA to generate an interpretable profile from a forensic sample. To determine the DNA quantity, a set of standard with known DNA concentrations are used to make a standard curve using ordinary least squares which is compared to samples with unknown quantities of DNA to determine the concentration. The goal of this research project was to examine two alternative methods in determining the quantity of DNA that does not require a standard curve for each run to minimize run-to-run variation and reduce costs and analyst time. These two methods are the use of an external standard curve and a virtual standard curve using different lot numbers, curve preparations by different analysts, and between instrument calibrations. Samples were quantified in duplicate, and a linear regression was determined utilizing the of the average of all runs to calculate the slope and y-intercept per variable and target to generate a virtual standard curve in the new HID Real-Time PCR Analysis Software v1.3. It was determined that the external standard curve method and virtual standard curve method were identical. Results showed there was no significance between instrument calibration and no difference between kit lots when comparing the assay specific curve to the virtual/external curve methods. For the virtual standard curve, there was no significant difference to the assay specific method. There was significant differences between pipetting from different analysts when looking at the different standards prepared. A recommendation from this research regarding the use of these techniques is to have as many analysts as possible pipetting. If more than one variable is introduced throughout the process, a new virtual standard curve needs to be generated. This study demonstrates the feasibility of the implementation of the virtual standard curve function into a case working laboratory workflow and that a laboratory can benefit using these methods.Item Examination Of The Duration Of Immersion In Water And Extent Of Pruning Observed On Fingertips(2022-05) Ross, SheenaIn the realm of forensic science, fingers are normally thought of as evidence for identification; however, it is imperative that the forensic science community understands other valuable evidence that fingers can provide in aquatic medicolegal death investigations and criminal nonfatal investigations. This research project examined the development of fingertip pruning during 120 minutes of immersion in warm tap water that was allowed to cool, instead of being held constant. Additionally, this research examined the dissipation of fingertip pruning for 60 minutes after removal from the water. This research utilized ImageJ, an image analysis software, to provide two measures of quantitative results: the amount of swelling of individual friction ridges at each time interval and the percentage of the overall fingertip surface area with visible pruning. The findings of this study indicated that friction ridges increased in width as the duration of immersion increased, with some variation. Additionally, the percentage of surface area covered by pruning had a strong correlation between duration of immersion in water and duration of time removed from water. Lastly, the changes in the fingertip condition occurred quickly, within 20 minutes, and even after two hours of water immersion, the most obvious presence of pruning dissipated within 30 minutes; this supported that fingertip pruning should be treated as transient evidence in aquatic criminal investigations.Item Factors Effecting Friction Ridge Transfer Through Gloves Used During Crime Scene Processing(2020) Wasserman, AliahA pillar of the crime scene processing curriculum, Locard’s Exchange Principle states that every place one goes, they take something with them and also leave a trace behind. The ultimate goal of crime scene processing is to collect valuable forensic evidence while minimizing the effects of Locard’s Exchange Principle. The use of personal protective equipment (PPE) is one of the most common ways the forensic community mitigates the risk of cross-contamination during crime scene processing. Through trial, error, and research, it is known that friction ridge detail can transfer through gloves. The objective of this research is to help the field of crime scene investigation to develop best practices for minimizing scene contamination by way of this transfer. Though the community agrees it is possible to deposit this detail, it is lesser known what practices can intensify that chance, and more importantly – what can prevent it. This research tests two sets of circumstances in an attempt to determine best practices for mitigating friction ridge transfer during crime scene processing. This study determines the effect of hand condition, glove size, and utilization of the double-gloving method on the transfer of friction ridge detail to a glass surface through nitrile examination gloves. The findings were that the condition of the hands prior to donning the glove(s) did not impact this transfer, but that wearing two pairs of gloves significantly reduced the occurrence of friction ridge detail on the deposition surface as compared to one pair of gloves.