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Tissue Variability Effects on Saw Mark Evidence in Bone

Grosso, Alicia (2020) Tissue Variability Effects on Saw Mark Evidence in Bone. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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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.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Grosso, AliciaARG103@pitt.eduARG103
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairSiegel,
Committee MemberJudd,
Committee MemberMooney,
Committee MemberArkush,
Date: 8 June 2020
Date Type: Publication
Defense Date: 19 March 2020
Approval Date: 8 June 2020
Submission Date: 9 March 2020
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 150
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Anthropology
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: bone tissue; forensic anthropology; skeletal trauma; saw mark analysis; validation study; nonhuman bone
Date Deposited: 08 Jun 2020 16:17
Last Modified: 08 Jun 2020 16:17


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