1 Book Cover Here Copyright © 2014, Elsevier Inc. All Rights Reserved Chapter 2 PHYSICAL EVIDENCE Development, Interpretation, Investigative Value Criminal Investigation: A Method for Reconstructing the Past, 7 th Edition

2 Copyright © 2014, Elsevier Inc. All Rights Reserved Forensic Science The word forensic is derived from the Latin forensis, meaning “forum” At least two major branches of forensic science are recognized – Criminalistics – Forensic Medicine

3 Copyright © 2014, Elsevier Inc. All Rights Reserved Forensic Science Criminalistics – Drug Analysis/Toxicology – Firearms and Toolmarks – Photography – Trace, Implant, and Digital Evidence – Instrumental Chemistry, Forensic Biology/DNA – Crime Scene Reconstruction Forensic Medicine – Anthropology and Psychiatry – Serology and Toxicology – Odontology

4 Copyright © 2014, Elsevier Inc. All Rights Reserved Criminalistics The Development and Interpretation of Physical Evidence – Report of the National Academy of Sciences Basic Concepts: Details in Physical Evidence – What are they? Morphology (structure & form) – How are they developed? – Contrast Optical and Analytical Instruments

5 Copyright © 2014, Elsevier Inc. All Rights Reserved Criminalistics Basic Concepts – Identification – Identity The Role of the Crime Laboratory Reconstruction: Are the Facts Consistent with the Story?? – Induce an Admission or Confession – Protect the Innocent – Provide Expert Testimony The O.J. Simpson Case: The Sock Evidence

6 Copyright © 2014, Elsevier Inc. All Rights Reserved Forensic Medicine: Investigative Value Forensic Pathology Toxicology Forensic Odontology Forensic Psychiatry – Law Enforcement – The Courts – The Correctional System

7 Copyright © 2014, Elsevier Inc. All Rights Reserved Clue Materials as Information Sources Fingerprints, Lip Prints, Ear Prints Firearms Semen, Other Biological Material, and DNA Profiling Documents Trace Evidence

8 Copyright © 2014, Elsevier Inc. All Rights Reserved Latent Fingerprints Natural Sources Environmental sources Controlling Factors – Surface – Finger pressure

9 Copyright © 2014, Elsevier Inc. All Rights Reserved Fingerprint Evidence Developing – Making Fingerprints Visible – Powders – Chemicals – Alternate Light Sources Ultraviolet rays Laser radiation Preserving Classifying & Identifying

10 Copyright © 2014, Elsevier Inc. All Rights Reserved Classifying & Identifying Fingerprints Classification: Ridge Line Details – Patterns and class characteristics – Ridge Counting: Loops – Ridge Tracing: Whorls Identification: Individualizations by Ridge Line Deviations – Identifying a Latent Print Fingerprint Exemplars: Sources Comparison of a Latent with a Known Fingerprint Number of Points Necessary for an Identification

11 Copyright © 2014, Elsevier Inc. All Rights Reserved Fingerprint: Additional Considerations Automated Fingerprint Identification Systems (AFISs) Evidentiary Value – How Long Do Fingerprints Last? Levels of Expertise Probative Value

12 Copyright © 2014, Elsevier Inc. All Rights Reserved Firearms Crime Scene Bullet or Cartridge & Suspected Weapon Make and Mechanical Condition of Gun – Description and Operating Condition – Bullet Trajectory – Accidental Discharge – Trigger Pull Restoration of Serial Numbers Shooting Distance Powder Traces on Gun Hand Weapon Recently Fired? – How Many Shots? Type and Model of Weapon Used

13 Copyright © 2014, Elsevier Inc. All Rights Reserved Blood Investigative Uses – Locate the Crime Scene – Identify the Weapon or Instrument – Develop Associative Evidence – Reconstruct How the Crime was Committed – Corroborate or Disprove an Alibi – Interrogate a Suspect Evidentiary Value

14 Copyright © 2014, Elsevier Inc. All Rights Reserved Semen, Other Biological Material, and DNA Profiling DNA – What is it? DNA – How is it analyzed? Newer DNA Technology – Short Tandem Repeats (STRs) – Mitochondrial DNA DNA – Investigative Use DNA Results – Evidence and Proof

15 Copyright © 2014, Elsevier Inc. All Rights Reserved Documents Handwriting and Hand-Printing Examinations Typewriting and Computer Printing Examinations Paper and Other Examinations

16 Copyright © 2014, Elsevier Inc. All Rights Reserved Glass and Trace Evidence Glass – Direction of Break – Which Bullet Hole Was Made First? Trace Evidence: very small physical evidence requiring special instruments in order to examine it – Fibrous substances – Particulate matter

17 Copyright © 2014, Elsevier Inc. All Rights Reserved Utility of Trace Evidence* 1.Reconstruct the event 2.Associate people, places, and things involved with the event 3.Surmise the occupations of the principals 4.Describe the environment or location involved in the event *Petraco (1986)

18 Copyright © 2014, Elsevier Inc. All Rights Reserved Conclusion Most common clue materials – Fingerprints – Firearms evidence – Blood Less common clue materials – Documents – Glass – Biological material Trace evidence frequently overlooked