A guide to the scientific interpretation of blood traces
Blood Traces provides an authoritative resource that reviews many of the aspects of the interpretation of blood traces that have not been treated with the thoroughness they deserve. With strict adherence to the scientific method, the authors - noted experts on the topic - address the complexities encountered when interpreting blood trace configurations. The book provides an understanding of the scientific basis for the use of blood trace deposits, i.e. bloodstain patterns, at crime scenes to better reconstruct a criminal event.
The authors define eight overarching principles for the comprehensive analysis and interpretation of blood trace configurations. Three of these principles are: blood traces may reveal a great deal of useful information; extensive blood traces, although present, may not always yield information relevant to questions that may arise in a given case; and a collection of a few seemingly related dried blood droplet deposits is not necessarily an interpretable “pattern”. This important resource:
- Provides the fundamental principles for the scientific examination and understanding of blood trace deposits and configurations
- Dispels commonly accepted misinformation about blood traces.
- Contains a variety of illustrative case examples which will aid in demonstrating the concepts discussed
Written for forensic scientists, crime scene investigators, members of the legal community, and students in these fields, Blood Traces presents the fundamental principles for the scientific examination of blood trace deposits and configurations.
Table of Contents
DEDICATION v
EPIGRAPH vii
TABLE OF CONTENTS ix
FOREWORD xvii
ACKNOWLEDGEMENTS xix
PREFACE TO BLOOD TRACES: INTERPRETATION OF DEPOSITION AND DISTRIBUTION xxi
1 Physical Evidence Record 1
1.1 Generation of Physical Evidence Record 1
1.1.1 Scene as a Recording Medium 1
1.1.2 Creation of Blood Traces 5
1.2 Capturing the Physical Evidence Record: Crime Scene Analysis 5
1.2.1 The Stages of Crime Scene Investigation 6
1.2.1.1 Scene Protection and Security 6
1.2.1.2 Evidence Recognition 8
1.2.1.3 Evidence Documentation 10
1.2.1.4 Evidence Recovery, Packaging, and Transportation 14
1.3 Reconstruction of Past Incidents from the Physical Evidence Record 17
1.3.1 Definition 17
1.3.2 Art or Science, or Both? 17
1.3.3 Importance of the Scientific Method 18
1.3.4 Reconstruction vs. Reenactment 18
1.3.5 Holistic Philosophy: Blood Trace Configuration Interpretation Is Only One Aspect of Reconstruction 19
References 20
2 Historical Perspective 21
2.1 Edgar Allen Poe and Sir Arthur Conan Doyle: History in Fiction 21
2.2 Hans Gross 22
2.3 History of Research in Blood Traces 22
2.4 Detective Charlie Chan: History in Film 23
2.5 Paul Kirk 23
2.6 Herbert MacDonell 25
2.7 Bloodstain Pattern Analysis Committees and Organizations 26
References 26
3 Characteristics of Liquids Including Blood 29
3.1 Physical Properties and Fluid Mechanics of Liquids 29
3.1.1 Surface Tension and Weber Number 29
3.1.2 Density 31
3.1.3 Newtonian and Non-Newtonian Fluids 31
3.1.4 Viscosity and Poiseuille’s Equation 32
3.1.5 Flow Stability, Reynolds Number, and Rayleigh Number 33
3.1.6 Viscoelasticity 34
3.1.7 Caveats 34
3.2 Physical Characteristics of Blood 35
3.2.1 Definition and Description of Blood 35
3.2.2 Factors that Influence Droplet Deposit Periphery 37
3.2.3 Factors that Influence Droplet and Deposit Size 38
3.2.4 Sedimentation and Hematocrit 40
3.3 Optical Properties of Blood Deposits 40
3.4 Physiological Characteristics of Blood 41
3.4.1 Hemostasis and Clotting 41
3.4.1.1 Postmortem Clotting 42
3.4.1.2 Lack of Clotting 42
3.5 Use of Blood Substitutes in Training and Simulations 43
References 44
4 Detection, Visual Enhancement, Identification, and Source Attribution of Blood Deposits and Configurations 47
4.1 Optical Visualization of Blood Trace Deposits 48
4.2 Catalytic Tests 52
4.3 Protein Stains 53
4.4 Blood Typing and DNA Technology 53
4.5 A Limitation of Laboratory SOPs 54
4.6 Ongoing and Future Research 55
4.7 Conclusion 58
References 58
5 Terminology, Typology, and Taxonomy 61
5.1 History of Terminologies Applied to Blood Trace Configurations 61
5.2 A Typology for Blood Trace Deposits 63
5.2.1 Contact Transfers 64
5.2.1.1 Figure(s): Static Contact Transfers 66
5.2.2 Noncontact Deposit Configurations 69
5.2.3 Arc (“Cast-off”) Deposit Configurations 69
5.2.4 Arterial Deposit Configurations 70
5.2.5 Droplet Trail Deposit Configurations 71
5.2.6 Airborne Droplets in Respiratory Airstreams 72
5.2.7 Radial (“Impact”) Spatter (Include Close-Up) 73
5.2.8 Secondary Spatter 74
5.2.8.1 Dropping Height Experiments 75
5.2.8.2 Dropping Volume Experiments 76
5.2.8.3 Various Substrates 77
5.2.8.4 Secondary Spatter Discussion 77
5.2.9 Spatter Associated with Gunshot Wounds 78
5.2.9.1 Patterns from Perforating (Through-and-through) Wounds 78
5.2.9.2 Backspatter from Entrance Wounds with No Exit (Penetrating Wounds) 80
5.2.9.3 Blood Traces from Blowback 80
5.2.10 Other Configurations 82
5.2.10.1 Flow Configurations 82
5.2.10.2 Pooling Configurations 82
5.2.10.2.1 Clotting, Serum Separation and its Significance 82
5.2.10.3 Diluted Blood Deposits 83
5.2.10.4 Significance of Voids 86
5.2.11 Post-Incident Events (“Artifacts”) 87
5.2.11.1 Human Attempts at Clean-Up 87
5.2.11.1.1 Inhibiting and Obscuring Cleaning Agents 87
5.2.11.1.2 Luminol and Investigative Leads 88
5.2.11.2 Animals and Insects 88
5.2.11.3 Unavoidable Environmental Events (i.e., Rain, Wind…) 90
References 92
6 Blood Droplet Dynamics and Deposit Formation 95
6.1 Blood Droplet Motion and Velocity Vectors 95
6.2 Angle of Impact 96
6.3 Blood Droplet Trajectory and Resulting Impact Geometry 98
6.4 Region of Convergence and Region of Origin 101
6.5 Equivalence of Relativistic Motion 104
6.6 Impact Mechanism and Blood Trace Deposit Formation 110
6.6.1 Impacts of Falling Droplets with Sessile Blood 114
6.7 Conclusion 116
References 116
7 Blood Trace Interpretation and Crime Scene/Incident Reconstruction 119
7.1 Principles of Blood Trace Reconstruction 119
7.2 Utility 126
7.2.1 Associative 126
7.2.2 Action 126
7.2.3 Positional 128
7.2.4 Directional 129
7.2.5 Temporal 129
7.2.6 Pattern Directed Sampling 130
7.3 Limitations, Problems, and Common Acceptance of the Status Quo 130
7.3.1 Lack of Teamwork and Potential Synergism Between Criminal and Scientist Investigator 130
7.3.1.1 Lack of Appreciation for the Contributions of the Scientist (or Undervaluing of the Scientist) 131
7.3.2 Potential Failures of the Scientist Investigator 132
7.3.2.1 Investigator Inexperience 132
7.3.2.2 Neglect of Scientific Principles 132
7.3.2.2.1 Misunderstanding and/or Misuse of the Scientific Method 132
7.3.2.2.2 Over-Interpretation 136
7.3.2.2.3 Opinion of a Scientist vs. Scientific Opinion 139
7.3.2.3 Deficiency in Scientific Integrity 139
7.3.2.4 Cognitive Biases 140
7.3.3 Pre- and Post-Event Artifacts 140
7.3.4 Risks Engendered by Limited or Erroneous Information 141
7.3.5 Problems with “Patterns” 142
7.3.5.1 General Problems 142
7.3.5.2 Patterns Involving a Limited Number or Detail of Traces 143
7.3.5.3 Chronological Sequencing 144
7.3.5.4 Effects Caused by Interaction of Blood and Target Surface 144
7.3.5.5 Configurations Observed after Application of Blood Presumptive and Enhancement Reagents 147
7.3.6 Problems with the Interpretation of Specific Blood Trace Configurations 148
7.3.6.1 False Expectation of Airborne Blood Droplets from the First Wounding 148
7.3.6.2 Limitations in Determining the Origin with the Radial Spatter Configurations 149
7.3.6.3 Measurement Uncertainty and Significant Figures 150
7.3.6.4 “Height of Fall” Estimations 151
7.3.6.5 Crude Age Estimations of Dried Blood Traces Based on Appearance 152
7.3.7 Experimental Design 152
7.4 Blood Trace Configuration Analysis as Part of a Holistic Approach to Reconstruction 154
References 155
8 Science and Pseudoscience 157
8.1 Science 157
8.1.1 The Need for a Generalist-Scientist in Crime Scene Investigation 157
8.2 Pseudoscience 158
8.2.1 The Pernicious Consequences with Respect to Reconstructions 158
8.2.2 Pseudoscience Characteristics 158
8.2.2.1 Isolation 159
8.2.2.2 Nonfalsifiability 159
8.2.2.3 Misuse of Data 160
8.2.2.4 Lack of Replicability 160
8.2.2.5 Claims of Unusually High Precision, Sensitivity of Detection, or Accuracy of Measurement 160
8.2.3 Hallmarks of a Pseudoscientist 160
8.2.3.1 Impenetrability 161
8.2.3.2 Ulterior Motives (Financial Gain/Recognition) 161
8.2.3.3 Lack of Formal Science Education 162
8.2.3.4 Unwillingness to Self-Correct 162
8.3 Bad Science 163
8.4 Conclusions 164
References 164
9 Modes of Practice and Practitioner Preparation and Qualification 167
9.1 Existing Modes of Crime Scene Investigation Practice 167
9.1.1 The Folly of Casting Technicians into the Roles of Scientists 169
9.2 Preparations and Qualifications of Practitioners 170
9.2.1 Education and Training 172
9.2.2 Experience 173
9.2.3 Mentoring 174
9.2.4 Professional Development 174
9.2.5 Peer or Technical Review 174
9.2.6 Certification & Qualification Standards 176
References 177
10 Interesting and Illustrative Cases 179
10.1 The Sam Sheppard Case 180
10.1.1 Case Scenario/Background Information 180
10.1.2 The Physical Evidence and Its Interpretation 180
10.1.3 Conclusions 182
10.1.4 Lessons 184
10.2 Knife in the Gift Bag 185
10.2.1 Case Scenario/Background Information 185
10.2.2 The Physical Evidence and Its Interpretation 185
10.2.3 Conclusions 186
10.2.4 Lessons 186
10.3 The Farhan Nassar Case 186
10.3.1 Case Scenario/Background Information 186
10.3.2 The Physical Evidence and Its Interpretation 187
10.3.3 Conclusions 190
10.3.4 Lessons 191
10.4 Passive Documentation 191
10.4.1 Case Scenario/Background Information 191
10.4.2 The Physical Evidence and Its Interpretation 192
10.4.3 Conclusions 193
10.4.4 Lessons 193
10.5 The British Island Holiday Case 194
10.5.1 Case Scenario/Background Information 194
10.5.2 The Physical Evidence and Its Interpretation 195
10.5.3 Conclusions 198
10.5.4 Lessons 198
10.6 Absence of Evidence is Not Evidence of Absence 199
10.6.1 Case Scenario/Background Information 199
10.6.2 The Physical Evidence and Its Interpretation 200
10.6.3 Conclusions 201
10.6.4 Lessons 201
10.7 Triple Homicide 202
10.7.1 Case Scenario/Background Information 202
10.7.2 The Physical Evidence and Its Interpretation 202
10.7.3 Conclusions 204
10.7.4 Lessons 204
10.8 The O.J. Simpson Case 205
10.8.1 Case Scenario/Background Information 205
10.8.2 The Physical Evidence and Its Interpretation 207
10.8.2.1 Trails of Blood Droplets and Footwear 207
10.8.2.2 The Blood on and in the Bronco 213
10.8.2.3 The Socks and EDTA Testing 214
10.8.2.4 The Envelope 218
10.8.2.5 The Hat and Gloves 220
10.8.3 Conclusions 221
10.8.4 Lessons 223
10.9 A Vertical Crime Scene 223
10.9.1 Case Scenario/Background Information 223
10.9.2 The Physical Evidence and Its Interpretation 224
10.9.3 Conclusions 228
10.9.4 Lessons 229
10.10 Tissue Spatter from a Large Caliber Gunshot 229
10.10.1 Case Scenario/Background Information 229
10.10.2 The Physical Evidence and Its Interpretation 229
10.10.3 Conclusions 230
10.10.4 Lessons 230
10.11 Shooting of a Driver 230
10.11.1 Case Scenario/Background Information 230
10.11.2 The Physical Evidence and Its Interpretation 231
10.11.3 Conclusions 233
10.11.4 Lessons 233
10.12 A Contested Fratricide 235
10.12.1 Case Scenario/Background Information 235
10.12.2 The Physical Evidence and Its Interpretation 236
10.12.3 Conclusions 238
10.12.4 Lessons 238
References 240
11 “Bad” Cases - Misleading or Incompetent Interpretations 241
11.1 David Camm 242
11.1.1 Case Scenario/Background Information 242
11.1.2 The Physical Evidence and Its Interpretation 242
11.1.3 Conclusions 250
11.1.4 Lessons 251
11.2 Dew Theory 252
11.2.1 Case Scenario/Background Information 252
11.2.2 The Physical Evidence and Its Interpretation 252
11.2.3 Conclusions 253
11.2.4 Lessons 254
11.3 Murder of an Off-Duty Police Officer 254
11.3.1 Case Scenario/Background Information 254
11.3.2 The Physical Evidence and Its Interpretation 255
11.3.3 Conclusions 261
11.3.4 Lessons 261
11.4 The Imagined Mist Pattern 262
11.4.1 Case Scenario/Background Information 262
11.4.2 The Physical Evidence and Its Interpretation 262
11.4.3 Conclusions 263
11.4.4 Lessons 263
11.5 Concealed Blood Traces 264
11.5.1 Case Scenario/Background Information 264
11.5.2 The Physical Evidence and Its Interpretation 264
11.5.3 Conclusions 265
11.5.4 Lessons 265
11.6 A Stomping Homicide - Misuse of Enhancement Reagents 266
11.6.1 Case Scenario/Background Information 266
11.6.2 The Physical Evidence and Its Interpretation 266
11.6.3 Conclusions 268
11.6.4 Lessons 268
References 268
12 More Broadly Assessed Cases: Going Beyond the Request 269
12.1 Gunshot to the Forehead and the Runaway Car 270
12.1.1 Case Scenario/Background Information 270
12.1.2 The Physical Evidence and Its Interpretation 270
12.1.3 Conclusions 271
12.1.4 Lessons 271
12.2 The Obscured Bloody Imprint 273
12.2.1 Case Scenario/Background Information 273
12.2.2 The Physical Evidence and Its Interpretation 274
12.2.3 Conclusions 278
12.2.4 Lessons 278
12.3 The Murder of a Deputy: Shooting in a Hospital Room 279
12.3.1 Case Scenario/Background Information 279
12.3.2 The Physical Evidence and Its Interpretation 280
12.3.3 Conclusions 281
12.3.4 Lessons 281
13 Widely Held Misconceptions 283
13.1 Blood Traces Produced by Gunshot Wounds 283
13.1.1 Introduction to Firearms and Wounding 283
13.1.2 Microvascularization and Experimental Laboratory Models 285
13.1.3 Proposed Models and Their Failure to Consider Microvascular Structures 288
13.2 The “Normal Drop” Claim 295
13.3 MacDonell Priority Claims Relative to the Seminal 1939
Balthazard et al. Paper 296
13.4 The Claimed Equivalence of Deposits Diameters and Drop Diameters 296
13.5 Ambiguous Trace Configurations 297
13.5.1 Configuration Issues 297
13.5.2 Fabric Issues 298
13.6 Issues with Interpretation of Asymmetrical Blood Projections from Impacts 302
References 302
14 Resources 305
14.1 Bloodstain Pattern Analysis Groups 305
14.1.1 SWGSTAIN 306
14.1.2 NIST OSAC Bloodstain Pattern Analysis Subcommittee 308
14.1.3 Organizations 309
14.2 Publications and Other Information Sources 310
14.2.1 Journals 310
14.2.2 Newsletters 311
14.2.3 Books 311
14.2.4 Internet Resources 311
14.3 Training and Education 311
14.3.1 Continuing Education 312
14.4 Proficiency Tests 312
References 312
15 Concluding Remarks and Looking to the Future 315
15.1 Importance of Science on the Front End 315
15.2 The Integration of Physical Evidence with Police Investigations 316
15.3 Troubling Developments and Perceptions 317
15.4 Testing Facilities & the Creeping Inversion 318
15.5 The Pernicious Effects and Fallout from Bloodstain Workshops 319
15.6 Future Directions 320
References 323
BIBLIOGRAPHY 325
APPENDIX1: FUNDAMENTALS REVISITED 341
