Dissertation/Thesis Abstract

Tissue Variability Effects on Saw Mark Evidence in Bone
by Grosso, Alicia Rose, Ph.D., University of Pittsburgh, 2020, 151; 27830294
Abstract (Summary)

To be scientifically valid under the “Daubert standards,” scientific testimony must be tested, subjected to peer review and publication, have a known or potential error rate, have maintained standards for its proper operation, and be widely accepted within the relevant scientific community (Daubert v. Merrell Dow Pharmaceuticals, Inc. 1993). Forensic research has demonstrated that tooth hop (TH) is a valuable measurement from saw-cut bones as it can be used to indicate the teeth-per-inch (TPI) of a saw in postmortem dismemberment cases; however, error rates of TPI estimation are still in infancy and our knowledge of how bone tissue affects TH measurements is unclear. The purpose of this research is to investigate the effects of tissue variability (through use of different taxa of known sex and age) on the accuracy and precision of TH measurements in bone to estimate TPI of the saw blade. This will further aid in the creation of error rates associated with TH measurements while also assessing the validity of nonhuman proxies in saw mark research. This researcher measured TH from human (280), pig (797), and deer (689) long bones cut by two saw blades of different tooth type; human remains are from one individual, while pig and deer are from multiple. 50 distance-between-teeth measurements before and after sawing were collected from each saw blade for comparison. ANOVA and F-tests were used to compare mean TH measurements and variance, respectively, by saw-species, species, sex, and number of TH in a chain (versus isolated cases of TH), with significance determined at the p < 0.05 level. It is concluded that significant differences in TH (mm) do not reflect significant differences in associated TPI ranges of suspect blades. With this knowledge, fresh deer and pig proxies may be used in TH research, although deer is less advisable. Forensic case reports should report mean TPI ± 1 TPI (narrow) and mean TPI ± 2 TPI (wide) intervals with a sample size indicating number of tooth hops measured. Tooth hops in longer chains did not greatly affect results, so cases of isolated tooth hops may be used to estimate blade TPI.

Indexing (document details)
Advisor: Siegel, Michael I.
Commitee: Judd, Margaret A., Arkush, Elizabeth N., Mooney, Mark P.
School: University of Pittsburgh
Department: Dietrich School Arts and Sciences
School Location: United States -- Pennsylvania
Source: DAI-A 82/3(E), Dissertation Abstracts International
Subjects: Physical anthropology, Forensic anthropology, Histology
Keywords: Bone, Nonhuman Bone, Saw Mark Analysis, Skeletal Trauma, Validation Study
Publication Number: 27830294
ISBN: 9798672196145
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