The author has further granted permission to Simon Fraser University to keep or make a digital co... more The author has further granted permission to Simon Fraser University to keep or make a digital copy for use in its circulating collection (currently available to the public at the "Institutional Repository" link of the SFU Library website <www.lib.sfu.ca> at: <http) and, without changing the content, to translate the thesis/project or extended essays, if technically possible, to any medium or format for the purpose of preservation of the digital work.
This research was developed with funding from Defense Advanced Research Projects Agency Agreement... more This research was developed with funding from Defense Advanced Research Projects Agency Agreement D20AC00007. The views, opinions and/or findings expressed are those of the authors and should not be interpreted as representing the official views or policies of the Department of Defense or the US Government. We are also appreciative of support from USDA Hatch grants and the University of Tennessee.
Postmortem swabs transferred to FTA ® cards can streamline disaster victim identifications. T... more Postmortem swabs transferred to FTA ® cards can streamline disaster victim identifications. Total Body Score (TBS) can be a quick field assessment to evaluate the degree of body decomposition. No relationship exists between Accumulated Degree Days (ADD) and DNA degradation. A TBS of 13 and below consistently yielded a full profile regardless of the sampling season or ADD.
Unmarked graves are difficult to locate once the ground surface no longer shows visible evidence ... more Unmarked graves are difficult to locate once the ground surface no longer shows visible evidence of disturbance, posing significant challenges to missing person investigations. This research evaluates the use of terrestrial LIDAR point data for measuring localized elevation change at human grave surfaces. Three differently sized human graves, one control-pit, and surrounding undisturbed ground, were scanned four times between February 2013 and November 2014 using a tripod-mounted terrestrial laser scanner. All the disturbed surfaces exhibited measurable and localized elevation change, allowing for separation of disturbed and undisturbed ground. This study is the first to quantify elevation changes to human graves over time and demonstrates that terrestrial LIDAR may contribute to multi-modal data collection approach to improve unmarked grave detection.
Mammalian decomposition provides pulses of organic matter to the local ecosystem creating ephemer... more Mammalian decomposition provides pulses of organic matter to the local ecosystem creating ephemeral hotspots of nutrient cycling. While changes to soil biogeochemistry in these hotspots have been described for C and N, patterns associated with deposition and cycling of other elements have not received the same attention. The goal of our study was to evaluate temporal changes to a broad suite of dissolved elements in soils impacted by human decomposition on the soil surface including: 1) abundant mineral elements in the human body (K, Na, S, P, Ca, and Mg), 2) trace elements in the human body (Fe, Mn, Se, Zn, Cu, Co, and B), and 3) Al which is transient in the human body but common in soils. We performed a four-month human decomposition trial at the University of Tennessee Anthropology Research Facility and quantified elemental concentrations dissolved in the soil solution, targeting the mobile and bioavailable fraction. We identified three groups of elements based on their temporal patterns. Group 1 elements appeared to be cadaver-derived (Na, K, P, S) and their persistence in soil varied based upon soluble organic forms (P), the dynamics of the soil exchange complex (Na, K), and gradual releases attributable to microbial degradation (S). Group 2 elements (Ca, Mg, Mn, Se, B) included three elements that have greater concentrations in soil than would be expected based on cadaver inputs alone, suggesting that these elements partially originate from the soil exchange (Ca, Mg), or are solubilized as a result of soil acidification (Mn). Group 3 elements (Fe, Cu, Zn, Co, Al) increased late in the decomposition process, suggesting a gradual solubilization from soil minerals under acidic pH conditions. This work presents a detailed longitudinal characterization of changes in dissolved soil elements during human decomposition furthering our understanding of elemental deposition and cycling in these environments.
Forensic Science International-genetics, May 1, 2017
Molecular human identification has conventionally focused on DNA sampling from dense, weightbeari... more Molecular human identification has conventionally focused on DNA sampling from dense, weightbearing cortical bone tissue, typically from femora or tibiae. A comparison of skeletal elements from three contemporary individuals demonstrated that elements with high quantities of cancellous bone yielded nuclear DNA at the highest rates, suggesting that preferentially sampling cortical bone may be suboptimal . Despite these findings, the reason for the differential DNA yields between cortical and cancellous bone tissues remains unknown. The primary goal of this work is to ascertain whether differences in bone microstructure can be used to explain differential nuclear DNA yield among bone tissue types observed by , with a focus on osteocytes and the three-dimensional (3D) quantification of their associated lacunae. Osteocytes and other bone cells are recognized to house DNA in bone tissue, thus examining the density of their lacunae may explain why nuclear DNA yield rates differ among bone tissue types. Lacunae were visualized and quantified using synchrotron radiation-based micro-Computed Tomographic imaging (SR micro-CT). Volumes of interest (VOIs) from cortical and cancellous bone tissues (n = 129) were comparatively analyzed from the three skeletons sampled for Mundorff and Davoren's (2014) study. Analyses tested the primary hypothesis that the abundance and density of osteocytes (inferred from their lacunar spaces) vary between cortical and cancellous bone tissue types. Results demonstrated that osteocyte lacunar abundance and density vary between cortical and cancellous bone tissue types, with cortical bone VOIs containing a higher lacunar abundance and density. We found that the osteocyte lacunar density values are independent of nuclear DNA yield, suggesting an alternative explanation for the higher nuclear DNA yields from bones with greater quantities of cancellous bone tissue. The use of SR micro-CT allowed for a scale of analysis that revealed a high range of variation in lacunar abundance in both tissue types. Moreover, high-resolution SR micro-CT imaging revealed potential soft tissue remnants within marrow spaces not visible macroscopically. It is hypothesized that soft tissue remnants observed among the trabeculae of skeletal elements with high quantities of cancellous bone tissue are responsible for the high nuclear DNA yields. These findings have significant implications for bone-sample selection for nuclear DNA analysis in a forensic context when skeletal remains are recovered from the ground surface.
Application of X-ray photoelectron spectroscopy to examine surface chemistry of cancellous bone and medullary contents to refine bone sample selection for nuclear DNA analysis
Journal of Analytical Atomic Spectrometry, 2019
X-ray photoelectron spectroscopy was used to evaluate differences in elemental composition of hum... more X-ray photoelectron spectroscopy was used to evaluate differences in elemental composition of human bone tissue types and identify soil infiltration.
Cadaver Decomposition and the Persistence of Human DNA in the Underlying Soil
The 85th Annual Meeting of the American Association of Physical Anthropologists, Atlanta, GA, 2016
Urban Anthropology: Case Studies from the New York City Medical Examiner's Office
Identifying human remains often begins with cleaning and imaging the material. Hot water macerati... more Identifying human remains often begins with cleaning and imaging the material. Hot water maceration is used to remove adherent soft tissue from bone and radiographs are taken to better visualize osseous details. Heat and radiation are known to have harmful effects on DNA, but their ability to degrade DNA when used for cleaning and imaging has not been well studied. To better understand their individual and combined effects on the recoverability of DNA from bone, skeletal samples were subjected to 1) hot water maceration (62 O C for 45 minutes); 2) CT scanning (0.6mm slices, 120KV, 10.4 seconds); 3) X-ray (50kVp, 150 mA, 0.03 seconds, 40 inches); and 4) all 3 treatments combined. Forty-eight DNA samples were extracted, quantified and amplified with the AmpFLSTR ® Identifiler ® system. Nearly all of the processed samples had reduced RFU values relative to the unprocessed samples, indicating some amount of genetic loss. This loss did not always translate into loss of profile completeness, since only a few samples had a reduction in the number of loci detected after processing. DNA yields were not significantly reduced by any one of the processing methods, however the results indicate that the damaging effects are additive. It is possible that processing may reduce a bone's DNA reservoir and as more procedures are preformed, the pool of available genetic information might be diminished. Many intrinsic and extrinsic factors can affect the recoverability of DNA from bone. Collecting a DNA sample prior to processing avoids the negative effects from hot water maceration and radiological imaging.
Postmortem Skeletal Microbial Community Composition and Function in Buried Human Remains
MSystems, Apr 26, 2022
Understanding the microbes that colonize and degrade bone has important implications for preserva... more Understanding the microbes that colonize and degrade bone has important implications for preservation of skeletal elements and identification of unknown human remains. Current research on the postmortem bone microbiome is limited and largely focuses on archaeological or marine contexts.
Anthropologist-Directed Triage
Elsevier eBooks, 2014
Abstract Identifying victims from mass fatality events requires the synchronization of several pr... more Abstract Identifying victims from mass fatality events requires the synchronization of several processes including, but not limited to, remains recovery, antemortem information collection, mortuary processes, death certification, family assistance, and finally, repatriation. Many different forensic disciplines are involved in recovering and identifying disaster victims. In particular, anthropologists have increasingly been involved with disaster victim identification in various roles from recovery and mortuary personnel to, more recently, management positions. This chapter discusses one small aspect of the mortuary process, triage, and its interplay with other aspects of identifying highly fragmented and commingled human remains. Specifically, this chapter focuses on anthropologist-directed triage and how it differed during three distinct mass fatality incidents: the World Trade Center disaster, the crash of American Airlines Flight 587, and the crash of the Staten Island Ferry. Each of these incidents involved significant variation in the number of victims, the number of recovered human remains, their degree of fragmentation, the site characteristics, and the recovery processes. Each of these considerations affected the triage teams’ composition and duties.
Re-examining so-called ‘secondary identifiers’ in Disaster Victim Identification (DVI): Why and how are they used?
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