The Forensic Analysis, Comparison and Evaluation of Friction Ridge Skin Impressions

Dan Perkins is a Senior Reporting Fingerprint Examiner and has been involved in fingerprint identification for over 20 years. Dan has held various other roles including Deputy Head of the Forensic Faculty and Fingerprint Training & Development Manager. He holds a Diploma in Forensic Human Identification (DipFHID) from the Royal College of Physicians.

Acknowledgements xi

Introduction 1

References 2

Part I Analysis Stage 5

1 Does the Mark Have Evidential Value? 7

1.1 Continuity and Integrity 7

1.2 The Most Evidentially Valuable Mark 11

References 12

2 Does the Mark Require Enhancement? 13

3 What Details Does the Mark Reveal? 15

3.1 Persistence and Uniqueness 15

3.2 Documentation 16

3.3 Complex Marks 17

3.4 First-Level Detail 21

3.5 Second-Level Detail 34

3.6 Third-Level Detail 44

3.7 Creases, Subsidiary Ridges and Scars 50

3.8 Abnormalities 60

References 61

4 Are the Details in the Mark Likely to Appear Similarly in a Print Made by the Same Area of Skin? 67

4.1 Downward Pressure 68

4.2 Movement 71

4.3 Superimposition 76

4.4 Colour Reversal 79

4.5 Direction Reversal 83

4.6 The Surface the Mark Was On 87

4.7 The Material the Mark Was Made In 91

4.8 The Media Used to Develop the Mark 92

4.9 Changes to the Skin 93

References 95

5 Is the Mark Suitable? 99

References 105

6 What Is the Most Likely Orientation of the Mark? 107

6.1 Shape and Ridge Flow 107

6.2 Pattern Family 108

6.3 Distal Flexion Crease 108

6.4 Other Marks 109

6.5 The Surface the Mark Was Found on 109

6.6 Summary 109

Reference 110

7 Which Area of Skin Is Most Likely to Have Made the Mark? 111

7.1 The Surface the Mark Was Found On 111

7.2 Other Marks 112

7.3 Lone Marks 119

7.4 The Part of the Digit That Made the Mark 122

7.5 The Pattern 124

7.6 Summary of Digit Determination 133

7.7 Palm Marks 134

7.8 Medial and Proximal Phalange Marks 150

7.9 Plantar Marks 152

7.10 Toe Marks 158

References 160

8 What Details Does the Print Reveal, and Are They Likely to Be a Reliable Record of the Details on the Skin of the Donor? 163

8.1 Sets of Fingerprints 163

8.2 The Details in the Print 166

8.3 The Reliability of the Details 168

References 171

Part II Comparison 173

9 Are the Details in the Mark in Agreement or Disagreement with Those in the Print? 175

9.1 First-Level Detail 176

9.2 Second-Level Detail 177

9.3 Third-Level Detail 180

9.4 Creases, Subsidiary Ridges and Scars 181

References 183

Part III Evaluation 185

10 Which Conclusion Is Supported by the Observations in the Analysis and Comparison? 187

10.1 Exclusion 190

10.2 Identification 196

10.3 Inconclusive 207

References 210

Appendices 215

Appendix 1 Fabrication, Transplantation and Forgery 215

A.1 Fabrication 215

A.2 Transplantation 219

A.3 Forgery 222

References 227

Appendix 2 Verification 229

A2.1 Open Verification 229

A2.2 Blind Verification 231

A2.3 The Use of Verification 232

A2.4 Technical Review 232

References 233

Appendix 3 Bias 235

A3.1 Contextual Information 235

A3.2 Experience 237

A3.3 Motivation 237

A3.4 How Bias Can Affect Decision Making 238

A3.5 Minimising the Effects of Bias 239

References 240

Appendix 4 Activity Level Propositions 243

A4.1 How Long Has the Mark Been on the Surface? 244

A4.2 What Were the Circumstances at the Time the Mark Was Made? 260

A4.3 Blood Marks 264

References 267

Appendix 5 Errors 273

A5.1 Clerical Errors 273

A5.2 Technical Errors 273

A5.3 Error Rates 284

References 300

Index 303