Blood Traces

Peter R. De Forest is Professor Emeritus of Criminalistics at the John Jay College of Criminal Justice, City University of New York. He has served as a scientific consultant on physical evidence issues for over sixty years.

Peter A. Pizzola is the former Laboratory Director and Assistant Commissioner of the New York City Police Crime Laboratory, former manager of the NYC Office of the Chief Medical Examiner Special Investigations Unit and Commanding Officer (retired) of the Yonkers Police Forensic Lab/Crime Scene Unit.

Brooke W. Kammrath is an Associate Professor of Forensic Science at the University of New Haven and Assistant Director of the Henry C. Lee Institute of Forensic Science. She also serves as a scientific consultant and expert witness for both criminal and civil cases.

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