ERASING THE EVIDENCE: THE IMPACT OF FIRE ON THE METRIC AND MORPHOLOGICAL CHARACTERISTICS OF CUT MARKS ____________ A Thesis Presented to the Faculty of California State University, Chico ____________ In Partial Fulfillment of the Requirements for the Degree Master of Arts in Anthropology ____________ by Ashley Hutchinson Fall 2010 ERASING THE EVIDENCE: THE IMPACT OF FIRE ON THE METRIC AND MORPHOLOGICAL CHARACTERISTICS OF CUT MARKS A Thesis by Ashley Hutchinson Fall 2010 APPROVED BY THE DEAN OF GRADUATE STUDIES AND VICE PROVOST FOR RESEARCH: Katie Milo, Ed.D. APPROVED BY THE GRADUATE ADVISORY COMMITTEE: _________________________________ Turhon A. Murad, Ph.D., Chair _________________________________ Eric J. Bartelink, Ph.D. DEDICATION To my loving family and fiancé, without your continued support throughout my education I would not be where I am today. iii ACKNOWLEDGMENTS The completion of my master’s thesis would not have been possible without my committee members, Dr. Turhon Murad and Dr. Eric Bartelink. Their continual guidance and patience have made all the difference. I greatly appreciate all time and effort which they have put into reading chapter drafts, providing their suggestions, and their input. I would also like to thank Steve Maletik and the Butte Fire Academy for the use of their facility. The realistic conditions which they have provided have made all the difference in the outcome of this research. Thank you to Shannon Clinkinbeard and the CSU-Chico Human Identification Lab for access to invaluable resources, and David Philhour for his statistical insight. Thank you to Dr. John DeHaan and Fire-Ex Forensics for the use of equipment and his extensive knowledge on burning. I am also thankful to the Chico Meat Locker; without them I would not have had a research sample. I am thankful to Melanie Beasley for her guidance during the initial stages of my thesis development. I would also like to thank my graduate cohort for all their support. We have shared some ups and downs over the last three years and I would not have made it through without them. iv Finally I would like thank my family and friends for all of their love and support. They are my emotional support and a constant reminder of what I am able to achieve. v TABLE OF CONTENTS PAGE Dedication................................................................................................................... iii Acknowledgments ...................................................................................................... iv List of Tables.............................................................................................................. viii List of Figures............................................................................................................. ix Abstract....................................................................................................................... x CHAPTER I. Introduction.............................................................................................. 1 Research Questions ...................................................................... 3 Organization of Thesis ................................................................. 4 II. Literature Review on Burning.................................................................. 7 Composition of Bone.................................................................... 8 Mechanism of Fire........................................................................ 9 Thermal Damage to Bone............................................................. 10 Previous Research on Burning ..................................................... 13 Summary....................................................................................... 20 III. Cut Mark Literature Review..................................................................... 21 Classifications of Tools and Cut Marks ....................................... 22 Effects of Sharp Force Trauma on Bone ...................................... 25 Previous Sharp Force Trauma Research....................................... 26 Summary of Sharp Force Trauma ................................................ 31 vi CHAPTER PAGE IV. Materials and Methods ............................................................................. 33 Materials....................................................................................... 33 Methods ........................................................................................ 39 Summary....................................................................................... 42 V. Results...................................................................................................... 43 Descriptive Analysis of the Pilot Study and Research Sample .... 43 Analysis of Statistical Results from Research Sample................. 47 Indications Based on the Analytical Results ................................ 54 Summary....................................................................................... 54 VI. Discussion................................................................................................. 56 Morphological Changes................................................................ 57 Discussion of Change in Cut Mark Size....................................... 62 Summary....................................................................................... 66 VII. Conclusion................................................................................................ 67 Implications .................................................................................. 69 Limitations of Study..................................................................... 69 Future Research............................................................................ 71 References Cited......................................................................................................... 73 Appendices A. Raw Cut Mark Data from Pilot and Research Sample ............................. 79 B. Data: Fire Temperature Recordings ......................................................... 83 vii LIST OF TABLES TABLE PAGE 1. Heat Related Fractures and Their Characteristics .................................... 12 2. Pre- and Post-Burn Measurements of the Research Sample..................... 48 3. Paired T-test Results for Pre vs. Post Burn Width Comparisons.............. 50 4. Description of Cut Marks and Data Recorded on Each Tool ................... 51 5. Survivorship Rate of Striations After Burning ......................................... 52 viii LIST OF FIGURES FIGURE PAGE 1. Tools Used to Create Cut Marks: a) Hand Saw, B) Cleaver, C) Steak Knife, D) Scalpel................................................................ 36 2. Research Sample Bones Prior to Burning: a) Saw, B) Scalpel, C) Knife, D) Cleaver ......................................................................... 38 3. Set up of Fuel with Research Sample and Heat Couplings in Place......... 39 4. Pilot Study Sample Post Burn and Research Study Sample Post Burn.... 45 5. Cleaver Marks Before Burning (Specimen D) ......................................... 46 6. Knife cut Marks on the Femoral Head (Specimen C)............................... 51 7. Post Burn Striations of the Eleventh Cut on the Anterior Surface of Specimen A (Saw) ........................................................................ 53 ix ABSTRACT ERASING THE EVIDENCE: THE IMPACT OF FIRE ON THE METRIC AND MORPHOLOGICAL CHARACTERISTICS OF CUT MARKS by Ashley Hutchinson Master of Arts in Anthropology California State University, Chico Fall 2010 The aim of this study is to provide a preliminary framework for understand- ing how fire affects the survivorship of cut marks on bone. This study analyzed the sur- vivorship of cut marks, striations, and metric changes of kerf size associated with burn- ing. There was an expectation that most cut marks would survive the fire, although changes were expected such as that the previous damage to bone would lead to exten- sive fracturing in the areas of the preexisting trauma. An understanding of how fire affects cut marks on bone is important when attempting to determine a particular class of tool based on cut mark features. Because the use of burning to hinder identification and destroy evidence are common challenges faced by forensic scientists, understanding that fire may change trauma characteristics is important when attempting to draw conclusions about a suspect weapon. With kerf x width being a criterion for assessing tool class, forensic investigators need to under- stand that if bone is burned, this method may not be able to be used to eliminate suspect weapons. For the purpose of this study cut marks were created on pig (Sus scrofa) femora using a cleaver, hand saw, scalpel, and steak knife. From these cut marks, casts were made and then analyzed using a digital microscope. The total number of cut marks present on each bone was noted, and widths were taken at three intervals along the length of each cut mark. Once casted, the pig femora were burned in a controlled build- ing fire for approximately 45 minutes with the temperature ranging from 277.3°C- 1,096°C. The surviving cut marks were casted again. The results from this study were quite variable between the different tools. With only 47.2 percent of the cut marks surviving the fire, the bone with cut marks cre- ated by the cleaver demonstrated extensive fracturing. Survivorship was much higher for the cut marks for the scalpel