Forensic DNA Trace Evidence Interpretation: Activity Level Propositions and Likelihood Ratios

Cover
Half Title
Title Page
Copyright Page
Table of Contents
Preface
Acknowledgements
About the Authors
Chapter 1 Principles of Evaluation
1.1 Probability
1.2 Bayes’ Theorem
1.3 The Likelihood Ratio
1.4 Principles of Evaluation
1.5 Hierarchy of Propositions
1.5.1 Sub-Level 2: Sub-Sub-Source
1.5.2 Sub-Level 1: Sub-Source
1.5.3 Level 1: Source
1.5.4 Level 2: Activity
1.5.5 Level 3: Offence
1.6 Scientist Working as Investigator versus Evaluator
1.7 Case Assessment and Interpretation
1.8 Practice Questions
References
Chapter 2 Evaluation of Observations Given Activity Level Propositions
2.1 What Are ‘Activity Level Evaluations’?
2.2 Why Are Activity Level Evaluations Needed?
2.2.1 Case Issue: Indirect Transfer
2.2.2 Case Issue: Contamination
2.2.3 Case Issue: Prevalence of DNA of a Known Individual
2.2.4 Case Issue: Prevalence of DNA of an Unknown Individual and Background DNA
2.2.5 Case Issue: Persistence Issues
2.2.6 Case Issue: Absence of DNA
2.3 Who Is Doing It?
2.4 Interpretation Fallacies and Concerns with Activity level Evaluation
2.4.1 Common Evidence Interpretation Fallacies
2.4.1.1 The Transposed Conditional (a.k.a. the prosecutor’s fallacy)
2.4.1.2 The Defence Fallacy
2.4.1.3 The Base Rate Fallacy
2.4.1.4 The Association Fallacy
2.4.1.5 The Probability of Another Match Error (or the birthday problem)
2.4.1.6 The Numerical Conversion Error
2.4.1.7 Selection Bias
2.4.1.8 The Individualisation Fallacy
2.4.1.9 The Conjunction Fallacy
2.4.1.10 Pseudodiagnosticity
2.4.2 Recurrent Concerns with Activity level Evaluations
2.4.2.1 The Information about the Alleged Crime Is Not Known or Not Specific
2.4.2.2 That the Scientific Data Available Is Not Adequate
2.4.2.3 That the Evaluations Infringe on the Duties of the Court
2.4.2.4 That the LR, or Bayesian Inference, Is Incompatible with the Legal Process
2.5 Introducing the Cases
2.5.1 Case 1: The Attempted Kidnap
2.5.2 Case 2: The Three Burglars
2.5.3 Case 3: The Family Assault
2.5.4 Case 4: The Gun in the Laundry
2.6 Final Words
2.7 Practice Questions
References
Chapter 3 Transfer, Persistence, Prevalence and Recovery of Biological Traces
3.1 Introduction
3.2 What Is TPPR (and associated terminology)?
3.3 Our Current Knowledge Base on TPPR
3.3.1 Transfer of Biological Materials
3.3.1.1 Who Transferred? (and how much?)
3.3.1.2 What Was Transferred?
3.3.1.3 How Was It Transferred?
3.3.1.4 Where Is the Material Transferred From?
3.3.1.5 Where Is the Material Transferred To?
3.3.2 Persistence of Biological Materials
3.3.2.1 Was the Item Exposed to Negative Circumstances?
3.3.2.2 What Happened to the Item After the Activity of Interest?
3.3.2.3 How Was the Item Handled During the Forensic Process?
3.3.3 Prevalence of Biological Materials
3.3.3.1 What Was Already There?
3.3.3.2 What Was Prevalent on Surfaces Interacting During or After the Activities of Interest?
3.3.3.3 What Has Been Added During the Forensic Process?
3.3.4 Recovery of Biological Materials
3.3.4.1 What Happened to the Item at Any Point in the Forensic Process?
3.3.5 The Transfer, Persistence, Prevalence and Recovery of Human Hairs
3.4 Designing Experiments on DNA TPPR and Sharing Their Results
3.4.1 Notes on Experimental Design and Purpose of a Study
3.4.2 Reporting Findings from a Study on TPPR
3.5 Practice Questions
References
Chapter 4 Structuring Case Information
4.1 Introduction
4.1.1 Propositions or Hypotheses
4.1.2 What Are Propositions
4.1.3 Task-Relevant Information
4.2 Formulating Propositions about Activities
4.2.1 General Guidance on Formulating Propositions
4.2.1.1 Propositions Must Be Relevant to the Court
4.2.1.2 Propositions Should Not Be Uncertain
4.2.1.3 Propositions Come in Pairs
4.2.1.4 Propositions as a ‘Package Deal’
4.2.1.5 Propositions Must Be Mutually Exclusive
4.2.1.6 Propositions Are Exhaustive
4.2.1.7 Propositions Must Be Specific
4.2.1.8 Propositions Should Not Include Results or Mechanisms
4.2.1.9 Propositions Should Be Concise
4.2.2 A Practical Approach to Formulating Propositions
4.2.2.1 Is It Disputed That an Activity Took Place?
4.2.2.2 If the Activity Itself Is Not Disputed, Who Performed the Activity?
4.2.2.3 What Alternative Routes for TPR or Prevalence of Materials Are Being Disputed?
4.3 Assumptions and Other Task-Relevant Case Information
4.3.1 Propositions
4.3.2 Assumptions
4.3.3 Undisputed Contextual Information
4.3.4 Shifting between Propositions, Assumptions and Undisputed Case Information
4.4 Case Examples
4.4.1 Case 1: The Attempted Kidnap
4.4.2 Case 2: The Three Burglars
4.4.3 Case 3: The Family Assault
4.4.4 Case 4: The Gun in the Laundry
4.5 No Scenario Presented by Either Prosecution or Defence
4.6 Practice Questions
4.7 References
Chapter 5 Basic Mechanisms of Evaluation
5.1 Introduction
5.2 Deriving LR Formula by Hand
5.2.1 Step 1: Proposition, Background Information and Assumptions
5.2.2 Step 2: Identify Pathways of Transfer
5.2.3 Step 3: Identifying Temporal Order
5.2.4 Step 4: Start the Basic LR Formula
5.2.5 Step 5: Complete the LR Derivation
5.2.6 Step 6: Assign Probabilities
5.2.7 Step 7: Calculate the LR
5.3 Case 1: The Attempted Kidnap
5.3.1 Case 1: LR Derivation Step 1
5.3.2 Case 1: LR Derivation Step 2
5.3.3 Case 1: LR Derivation Step 3
5.3.4 Case 1: LR Derivation Step 4
5.3.4.1 Starting with a Demonstration of the First Method
5.3.5 Case 1: LR Derivation Step 5: Short-Hand Version of LR Derivation
5.3.5.1 Using the Pathways to Obtain the LR Formula
5.3.6 Case 1: LR Derivation Step 6: Assigning Probabilities
5.3.6.1 Incorporating Prior Belief with Data to Assign Probabilities
5.3.6.2 The Difference between Proportions and Rates
5.3.7 Case 1: LR Derivation Step 7: Calculating the LR
5.4 Case 2: The Three Burglars
5.4.1 Case 2: Step 1: Proposition, Background Information and Assumptions
5.4.2 Case 2: Step 2: Identify Pathways of Transfer
5.4.3 Case 2: Step 3: Identifying Temporal Order
5.4.4 Case 2: Step 4: Start the Basic LR Formula
5.4.5 Case 2: Step 5: Complete the LR Derivation
5.4.6 Case 2: Step 6: Assign Probabilities
5.4.7 Case 2: Step 7: Calculate the LR
5.4.8 Case 2: Supplemental
5.5 Case 3: The Family Assault
5.5.1 Case 3: Step 1: Proposition, Background Information and Assumptions
5.5.2 Case 3: Step 2: Identify Pathways of Transfer
5.5.3 Case 3: Step 3: Identifying Temporal Order
5.5.4 Case 3: Step 4: Start The Basic LR Formula
5.5.4.1 Case 3: Using Presence/Absence of DNA
5.5.4.2 Case 3: Using High/Low/None Categories of DNA
5.5.5 Case 3: Step 5: Complete the LR Derivation
5.5.5.1 Presence/Absence of DNA
5.5.5.2 High/Low/None Categories of DNA
5.5.6 Case 3: Step 6: Assign Probabilities
5.5.6.1 Presence/Absence of DNA
5.5.6.2 High/Low/None Categories of DNA
5.5.7 Case 3: Step 7: Calculate the LR
5.5.7.1 Presence/Absence of DNA
5.5.7.2 High/Low/None Categories of DNA
5.5.8 Case 3: Supplemental
5.6 Factors to Consider When Assigning Probabilities
5.6.1 Assigning Probabilities from Continuous DNA Amount to Binary DNA Presence
5.6.2 Observations Other Than DNA Amount
5.6.3 How to Obtain Data to Inform Probabilities
5.7 Final Words
5.8 Practice Questions
5.9 References
Chapter 6 Fundamentals of Bayesian Networks
6.1 Introduction
6.2 What Are Bayesian Networks?
6.3 How Do They Work?
6.3.1 A Two-Node Paternity Example
6.3.2 A Convergent Three-Node BN Example
6.3.3 A Divergent BN Example
6.4 How to Construct a BN for a Case?
6.4.1 BN Construction Software
6.4.1.1 GeNIe
6.4.1.2 BNlearn/gRain
6.4.1.3 HUGIN
6.4.1.4 AgenaRisk
6.4.2 Steps to Constructing a BN for an Evaluation, Given Activity-Level Propositions
6.5 Case 1: The Attempted Kidnap
6.5.1 Case 1 – Step 1: Define Proposition Node
6.5.2 Step 2: Define Activity Node(s)
6.5.3 Step 3: Group Similar Results
6.5.4 Step 4: Define Observations Node(s)
6.5.5 Step 5: Define Transfer and Persistence Node(s)
6.5.6 Step 6: Define Root Nodes(s)
6.5.7 Step 7: Checking for Absolute Support within the BN
6.6 Final Words on BN Construction
6.6.1 The Choice of BN Complexity
6.6.2 Variants on the BN for Case 1
6.7 Case 2: The Three Burglars
6.7.1 Step 1
6.7.2 Step 2
6.7.3 Step 3
6.7.4 Step 4
6.7.5 Step 5
6.7.6 Step 6
6.7.7 Step 7
6.7.8 Evaluation Case 2
6.8 Case 3: The Family Assault
6.8.1 Step 1
6.8.2 Step 2
6.8.3 Step 3
6.8.4 Step 4
6.8.5 Step 5
6.8.6 Step 6
6.8.7 Step 7
6.8.8 Evaluation
6.9 Practice Questions
6.10 References
Chapter 7 Advanced Mechanisms of Evaluation
7.1 Introduction
7.2 Using Intervals in BNs
7.2.1 Numbered Nodes
7.2.2 Interval Nodes
7.2.2.1 Summing Interval Nodes
7.2.2.2 Multiplying Interval Nodes
7.3 Case 4: The Gun in the Laundry
7.4 Modelling Effects and Amounts in BNs
7.4.1 BN Construction for Case 4
7.4.2 How to Model DNA Amounts as Distribution
7.4.3 How to Model Transfer Proportion
7.5 General Thoughts on Modelling
7.5.1 How to Model
7.5.1.1 Linear Regression
7.5.1.2 Logistic Modelling
7.5.1.3 Modelling with Bayesian Statistics
7.5.2 Making Modelling Decisions
7.6 Object-Oriented Bayesian Network (OOBN)
7.6.1 Theory of OOBNs
7.6.2 Creating an OOBN in HUGIN
7.7 Practice Questions
7.8 References
Chapter 8 Testing Robustness of Evaluation
8.1 Robustness vs Sensitivity vs Error Rates
8.1.1 Error Rates
8.1.2 Confidence Intervals
8.1.3 Measurement Error
8.1.4 The Probability of a Probability
8.1.5 Conservatism
8.1.6 Calculating a Bayes Factor
8.1.7 Sensitivity Analyses
8.2 Types of Sensitivity Analyses
8.2.1 Sensitivity Analysis for a Factor That Has Two States
8.2.2 Sensitivity Analysis for Two Factors That Each Have Two States
8.2.3 Sensitivity Analysis for Factors That Have More Than Two States
8.2.4 Resampling the Raw Count Data
8.2.5 Sample the Data and Not the Term
8.2.6 Sample the Term and Not the Data
8.2.7 Resampling Modelled Data
8.2.7.1 Propositions
8.2.7.2 Background
8.2.8 Sensitivity to the Results
8.2.9 Sensitivity to the Unknown Aspects of the Case Circumstances
8.2.10 Sensitivity to the Choice of Discretisation
8.2.11 Sensitivity to the BN Architecture
8.3 Setting Up Sensitivity Analyses in a Bayesian Network
8.3.1 Setting Up the Individual Sensitivity Nodes
8.3.2 Setting Up the Case Results Node
8.3.3 Setting Up the LR Calculation Node
8.3.4 Carrying Out the Sensitivity Analysis
8.3.5 The Sensitivity Node Setup for the Family Assault
8.4 Final Word on Sensitivity Analyses
8.5 Practice Questions
8.6 References
Chapter 9 Cell Type Testing
9.1 Introduction
9.2 Cell Type Testing
9.2.1 Screening Methods
9.2.1.1 Non-invasive Screening
9.2.1.2 Invasive Screening
9.2.2 Cell Type Testing Methods
9.2.2.1 Protein-Based Tests
9.2.2.2 Biochemical Tests
9.2.2.3 DNA-Based Testing
9.2.2.4 RNA-Based Testing
9.2.2.5 Testing Based on Microbiome
9.3 Evaluation of Cell Type Testing Results
9.3.1 Examples of Models for Interpretation of Test Results
9.3.2 Whose Prior?
9.3.3 What Are We Testing?
9.3.4 Cross-Reactivity or False Positive Test Results?
9.3.5 Degradation of What?
9.4 Cell Type Attribution to Donor
9.5 Incorporating Cell Type Testing to Address Activity-Level Issues
9.5.1 How Is the Result Defined?
9.5.2 Discretisation of the Results
9.5.3 Combining Cell Type Test Results with DNA Analysis
9.6 Addressing the Issue in the Case at the Source or Activity Level?
9.7 Example Case 3 – ‘The Family Assault’
9.8 Practice Questions
9.9 References
Chapter 10 Reporting
10.1 Introduction
10.2 Guidance on Evaluative Reporting
10.2.1 The Association of Forensic Science Providers (AFSP) – 2009
10.2.2 Guidance from Workshop ‘Legal Expressionism’ – 2011
10.2.3 Australian Standard 5388.4 – 2013
10.2.4 The European Network of Forensic Science Institutes (ENFSI) – 2015
10.2.5 Royal Statistical Society (RSS) Practitioner Guides – 2010–2015
10.2.6 The National Institute of Forensic Science (NIFS) – 2017
10.2.7 The Supreme Court of Victoria (Australia) – 2017
10.2.8 The International Society for Forensic Genetics (ISFG) – 2020
10.2.9 Summary of Recommendations for Reporting Given Activity-Level Propositions
10.3 Verbal Equivalents
10.4 Other Forms of Communication
10.4.1 Providing an Investigative Opinion
10.4.2 Sharing Results from a Case Pre-assessment
10.4.3 Court Testimony
10.5 Example Reports
10.6 Practice Questions
10.7 References
Chapter 11 Implementation
11.1 Considerations for the Laboratory and the Criminal Justice System
11.1.1 Who Will Be Requesting the Work, i.e. Judges/Lawyers/Police/Scientists?
11.1.2 What Type of Cases Will It Be Applied To?
11.1.3 How Many People Will Be Trained?
11.1.4 How Will People Be Trained/Deemed Competent?
11.1.5 How Will Information Be Disseminated to Stakeholders?
11.1.6 How Will Evaluations Be Carried Out (Will the Software Be Required)?
11.1.7 Will the Process Be Accredited?
11.1.8 What Will the Policy Be on Data Collection?
11.2 Training Resources
11.3 Case Information Management
11.4 Casework Workflow
11.5 Examples of Standard Operating Procedures (SOPs)
11.5.1 Case Acceptance/Initiation
11.5.1.1 Preface and Background
11.5.1.2 Scope
11.5.1.3 Procedure
11.5.2 Example of a Review Checklist
11.5.3 Carrying Out Activity-Level Evaluations
11.5.3.1 Preface and Foreword
11.5.3.2 Scope
11.5.3.3 Definitions and Abbreviations
11.5.3.4 Principle
11.5.3.5 Procedure
11.5.3.6 Setting Activity-Level Propositions
11.5.3.7 Sensitivity Analyses
11.5.3.8 Preparation of Reports
11.5.3.9 Case Review
11.5.3.10 Case Cancellation
11.5.3.11 Validation
11.5.4 Training Staff to Become Activity-Level Evaluators
11.5.4.1 Objectives
11.5.4.2 Method of Instruction
11.5.4.3 Method of Evaluation
11.5.5 BN Construction or LR Derivation
11.5.5.1 Preface and Foreword
11.5.5.2 Scope
11.5.5.3 Definitions and Abbreviations
11.5.5.4 Principle
11.5.5.5 Procedure
11.5.5.6 Sensitivity Analyses
11.6 Practice Questions
11.7 References
Chapter 12 Beyond Forensic Biology
12.1 Introduction
12.2 On Transfer of Marks, Materials and Signals
12.3 Welcome to the Forensic Biology Family
12.3.1 Bloodstain Pattern Analysis
12.3.2 Fingermarks
12.3.3 Non-human Biological Traces
12.3.3.1 Species Identification
12.3.3.2 Microbiome
12.4 Other Traces, Marks and Signal Data Given Activity-Level Propositions
12.4.1 The Relevant Population
12.4.2 A Broader Scope in Scenario Testing
12.4.2.1 DNA and Other Particulate Traces
12.4.2.2 DNA and Marks
12.4.2.3 DNA and Signals
12.4.3 Standardisation of Modelling Across Disciplines
12.4.4 Boundaries of Expertise
12.5 Combining Evidence
12.5.1 Interdisciplinary Evaluations Using Bayesian Networks
12.5.2 Interdisciplinary Evaluations Using Evidence Schemes
12.5.3 Multi-case Evaluations
The Case of the Newspaper Delivery Lady
12.6 References
Chapter 13 Looking to the Future
13.1 After Reading This Book
13.2 Current Trends in Research
13.2.1 Advances in Tests Performed and Data Collected
13.2.2 Advances in TPPR Studies
13.2.3 Advances in Evaluation Tools and Framework
13.2.4 Implications for Crime Scene Procedures
13.2.5 Acceptance in Court
13.3 References
Chapter 14 Answers to Practice Questions
Chapter 1 – Answers to Questions
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Chapter 2 – Answers to Questions
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Chapter 3 – Answers to Questions
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Chapter 4 – Answers to Questions
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Chapter 5 – Answers to Questions
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Chapter 9 – Answers to Questions
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Chapter 10 – Answers to Questions
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Index