Chapter 4 Forensics/Physical Evidence

Types of Evidence Physical Evidence Direct Evidence Circumstantial/ Indirect Evidence Trace Evidence Associative Evidence Prima Facie Evidence Corpus Delicti Evidence Probative Evidence Exculpatory Evidence

Processing Physical Evidence Discovering, recognizing and examining it; Collecting, recording and identifying it; Packaging, conveying and storing it; Exhibiting it in court; and Disposing of it when the case is closed.

Evidence Material Evidence – evidence that is relevant to the specific case and forms a substantive part of the case or that has a legitimate and effective influence on the decision of the case. Relevant Evidence – evidence that applies to the matter in question. Competent Evidence – evidence that has been properly collected, identified, files and continuously secured.

Common Errors in Collecting Evidence Not collecting enough of the sample Not obtaining standards of comparison Not maintaining the integrity of the evidence

Types of Fingerprints Latent fingerprints: impressions transferred to a surface. Visible fingerprints: prints made when fingers are dirty or stained. Plastic fingerprints: impressions left in soft substances. Invisible fingerprints: prints that are not readily seen but can be developed through powders or chemicals.

Dusting for Fingerprints 1. Make sure the brush is clean 2. Shake the powder can to loosen powder 3. Remove all excess powder 4. Photograph

Daubert Standard Two-prong standard: 1. Expert testimony must be reliable. 2. Expert testimony must be relevant.

Determining Reliability Can the scientific theory or technique be tested and has it been tested? Has it been the subject of publication or peer review? What is the known or potential rate of error? What are the standards controlling the technique’s operation? Has the theory or technique been generally accepted in the scientific community?

Frequently Examined Evidence I Fingerprints Voiceprints Language Analysis DNA Profiling Blood and Other Body Fluids Hairs and Fibers Shoe and Tire Impressions Bite Marks Tools and Tool Marks Firearms and Ammunition

Firearm Properties to Note Make Serial Number Caliber Model Type Finish Any Unusual Characteristics

Firearm Terminology Bore – the diameter of the inside of a weapon’s barrel Lands – two opposing ridges in the barrel Straie – scratches on recovered bullets Caliber – the diameter of the bullet intended to be used with a specific weapon

Glass Microscopic examination: proves that two pieces were once one piece. Spectrographic analysis: determines the elements of the glass. Physical comparisons.

Frequently Examined Evidence II Glass Soils and Minerals Safe Insulation Ropes, Strings, and Tapes Documents –Best evidence rule Drugs Laundry and Dry- cleaning Marks Paint Skeletal Remains Wood Other types

Skeletal Remains Forensic anthropology: uses techniques that have been developed during decades of research by physical anthropologists and archaeologists. Forensic entomology: the science of studying insects found at the scene of a death.

Evidence Admissibility in Court 1. Identify the evidence as that found at the crime scene 2. Describe where it was found 3. Establish the chain of custody from discovery to the present 4. Explain any changes that have occurred in the evidence