Investigative Techniques

Unit 03: Investigative Techniques in Criminal Investigations

Overview

• Focus on the effectiveness and limitations of various investigative techniques used in criminal investigations.

• Key transitions from crime scene to courtroom.

Page 1: Crime Scene Identification

• Crime Scene Management: Properly marked crime scenes are crucial to avoid contamination.

  • Not Cross Signs: Indicates restricted access to ensure evidence integrity.

Page 2: Assessing Investigative Techniques

• Useful Techniques: Assess the value of different methods to solve criminal cases.

  • Focus on how these methods transition from crime scene analysis to courtroom evidence.

Page 3: DNA as an Investigative Technique

• Utility of DNA:

  • Present in nearly every human cell; unique to individuals facilitating reliable identification.

  • Solves cold cases and can affirm both guilt and innocence.

  • Aids in victim identification when no other methods are applicable.

  • Familial DNA: Similarities observed in DNA from relatives can aid investigations.

Page 4: Limitations of DNA Evidence

• Cross-Contamination: Risks of DNA samples being compromised.

• National DNA Database Dependence: A match requires profiles to be in the database leading to concerns about civil liberties.

• False Implication Risk: Small traces might inaccurately link innocent individuals to crimes.

• Cost of Testing: Expense associated with DNA analysis.

Page 5: Case Study Research

• Research Task: Investigate the cases of Colette Aram and Anne Marie Foy.

  • Note the role of forensic evidence, particularly DNA, in each case.

Page 6: Surveillance Techniques

• CCTV as a Primary Tool:

  • Essential for capturing evidence and identifying suspects post-crime.

  • Particularly effective in urban environments where high volumes of street crime occur.

• Covert Surveillance: Utilization of human intelligence to gather information discreetly, involving personal relationships for data collection.

Page 7: Criminal Profiling Introduction

• Understanding Offenders: Behavior is often reflective of past actions; prior violence predicts future potential for violence.

Page 8: Profiling Definitions

• General Definition: Compiling known data about a crime scene and victim to construct a potential profile of the unidentified perpetrator (Ainsworth, 2001, p7).

Page 9: Types of Profiling

• Geographical Profiling: Bottom-up approach that uses location data to suggest potential perpetrators.

• Investigative Psychology: Merges offender profiling with databases to derive offender characteristics.

• Typological Profiling: Top-down method categorizing offenders as organized or disorganized based on their criminal behavior.

Page 10: Organized vs. Disorganized Crime

• Organised Crime:

  • Features: Planned, targeted victims, premeditated violence.

  • Characteristics: Intelligent offenders who retain control, socially adept.

  • Examples: Robbery, trafficking.

• Disorganized Crime:

  • Features: Impulsive and random acts, lack of planning.

  • Characteristics: Socially inept offenders; often leave evidence behind.

  • Example: Case of Jack the Ripper.

Page 11: Profiling Characteristics

• Profiles include demographics like age, gender, occupational background, IQ, and familial connections.

• Use of profiles aids in connecting suspects to crimes via matching evidence and constructing a solid case for prosecution in court.

Page 12: Limitations of Profiling

• Reliability Issues: Many profiles stem from interviews with serial offenders, raising validity concerns.

• Overlap of Crime Categories: Some offenders do not fit neatly into organized or disorganized categories.

• Scientific Limitations: Profiling may be vague and universally applicable (Barnum Effect).

Page 13: The Barnum Effect

• Definition: The tendency of individuals to accept generic statements as personally relevant.

• Common pitfalls in profiling methods due to this phenomenon.

Page 14: Eyewitness Testimony (EWT)

• Definition: Testimony provided by individuals who have witnessed a crime, considered highly reliable by juries.

• Limitations: Factors such as stress and anxiety can compromise accuracy; skepticism exists regarding EWT under certain conditions.

Page 15: Expert Witnesses

• Role of Experts: Provide specialized knowledge and interpret evidence effectively.

  • Blood Pattern Analysis: Helps in understanding assault dynamics.

  • Digital Forensics: Recovery of deleted data including messages and contacts.

  • Entomology in Investigations: Assists in determining timelines of suspicious deaths.

Page 16: Conclusion on Expert Witnesses

• Key role in gathering, analyzing, and explaining evidence to support criminal investigations, enhancing the overall evidentiary framework in court.