Forensic Sci Med Pathol (2011) 7:53–62 DOI 10.1007/s12024-010-9185-6 T E C H N I C A L R E P O R T Statistical analysis of kerf mark measurements in bone James A. Bailey • Yishi Wang • Frank R. W. van de Goot • Reza R. R. Gerretsen Accepted: 6 July 2010 / Published online: 23 July 2010 The Author(s) 2010. This article is published with open access at Springerlink.com Abstract Saw marks on bone have been routinely reported in dismemberment cases. When saw blade teeth contact bone and the bone is not completely sawed into two parts, bone fragments are removed forming a channel or kerf. Therefore, kerf width can approximate the thickness of the saw blade. The purpose of this study is to evaluate 100 saw kerf widths in bone produced by ten saw types to determine if a saw can be eliminated based on the kerf width. Five measurements were taken from each of the 100 saw kerfs to establish an average thick- ness for each kerf mark. Ten cuts were made on 10 sections of bovine bone, ﬁve with human-powered saws and ﬁve with mechanical-powered saws. The cuts were examined with a stereoscopic microscope utilizing digital camera measuring software. Two statistical cumulative logistic regression models were used to analyze the saw kerf data collected. In order to estimate the prediction error, repeated stratiﬁed cross-validation was applied in analyzing the kerf mark data. Based on the two statistical models used, 70–90% of the saws could be eliminated based on kerf width. J. A. Bailey (&) Department of Political Science and Law Enforcement, Minnesota State Universiy Mankato, Mankato, Minnesota 56001, USA e-mail: james.bailey@mnsu.edu; jbailey30@ec.rr.com J. A. Bailey 617 Chestnut Street, Wilmington, North Carolina 28401, USA Y. Wang Department of Mathematics and Statistics, University of North Carolina Wilmington, 601 S. College Road, Wilmington, North Carolina 28401-5970, USA e-mail: Wangy@uncw.edu Keywords Tool marks Saw marks Kerf mark analysis Dismemberment Introduction Postmortem dismemberment cases, sometimes referred to in the media as corpse mutilation, abuse of corpse or criminal dismemberment, present a challenge to investi- gators attempting to identify the tool used in the dismem- berment [1]. If multiple tools are recovered, examinations could be conducted to link or eliminate each of the tools used in the dismemberment. Postmortem dismemberment is typically accomplished with a knife, axe, saw or a combination of these cutting tools. When these types of cutting tools are used, they can leave tool marks on carti- lage and bone. Sometimes these marks can be used to match or eliminate the tool [2, 3]. Even if the cutting tool cannot be matched or eliminated, an examination of the tool marks can provide some information about the general characteristics of the tool [4, 5]. F. R. W. van de Goot Department of Pathology, Vrije Universiteit Medisch Centrum, Centrum voor Forensische Pathologie, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands e-mail: FRW.Goot@vumc.nl R. R. R. Gerretsen Department of Pathology, Netherlands Forensic Institute (NFI), Laan van Ypenburg 6, 2497 GB The Hague, The Netherlands e-mail: r.gerretsen@nﬁ.minjus.nl R. R. R. Gerretsen Barge’s Anthropologica, Leiden University Medical Center (LUMC), Leiden, The Netherlands 123