Forensics/Physical Evidence

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Chapter 4

• Forensics/Physical Evidence

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Types of Evidence

• Physical Evidence
• Direct Evidence
• Circumstantial/ Indirect Evidence
• Trace Evidence
• Associative Evidence

• Prima Facie Evidence
• Corpus Delicti Evidence
• Probative Evidence
• Exculpatory Evidence

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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.

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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.

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Common Errors in Collecting Evidence

• Not collecting enough of the sample
• Not obtaining standards of comparison
• Not maintaining the integrity of the evidence

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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.

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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

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Daubert Standard

• Two-prong standard
• Expert testimony must be reliable.
• Expert testimony must be relevant.

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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
  techniques operation?
• Has the theory or technique been generally
  accepted in the scientific community?

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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

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Firearm Properties to Note

• Make
• Serial Number
• Caliber
• Model
• Type
• Finish
• Any Unusual Characteristics

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Firearm Terminology

• Bore the diameter of the inside of a weapons
  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

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Glass

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

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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

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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.

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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

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