Forensic Science and Criminalistics Overview

Role of a Forensic Scientist: Collecting and testing physical evidence, serving as an expert witness, and teaching.
Expert Witness: Individual with above-average knowledge; can provide interpretations and opinions, unlike eyewitnesses who only state observations.
Individual Evidence: Specific to one source (e.g., DNA, Fingerprints).
Class Evidence: Shared by a group (e.g., Blood type, shoe size).
RMP (Random Match Probability): Probability that an unrelated person shares the same characteristics.
Locard Principle: "Everyone leaves a trace."
Chain of Custody: Essential list of individuals in possession of evidence to ensure authenticity and admissibility.
Gatekeeper: The trial judge who determines if evidence is admissible.

Sir Arthur Conan Doyle: Popularized trace evidence and logic in literature.
Mathieu Orfila: "Father of Toxicology"; detected poisons in the body.
Alphonse Bertillon: Created the Anthropometry System using 11 body measurements ( $\text{Height, Stretch, Bust, etc.}$ ).
Francis Galton: Developed fingerprinting classification.
Leone Lattes: Determined blood types from dried stains via the "Lattes Test."
Calvin Godard: Used microscopes for ballistics matching.
Albert Osborn: Founded questioned document analysis.
Hans Gross: Treated investigation as a science.
Edmond Locard: "Father of Forensic Science"; known for the Principle of Exchange.

Primary Scene: Original location of the crime.
Secondary Scene: Location where additional evidence is found.
Personnel Roles:
- Police Officers: Secure the scene.
- CSI Unit: Document and collect evidence.
- District Attorney: Determines search warrant requirements.
- Medical Examiner: Determines preliminary cause of death.
- Detectives: Interview witnesses and lead investigations.
Protocol: Interview $\rightarrow$ Examine $\rightarrow$ Document $\rightarrow$ Process.
Witness Factors: Age (children and elderly have high mistake rates in absent suspect lineups) and Cross Race Effect (CRE).

Forensic Anthropology: Study of skeletal remains for identification (gender, age, race).
Determining Gender: The pelvis is the most accurate (female is wider/rounded; male is narrower/pointed). The skull is the second best (male is more square/sloping).
Determining Age: Teeth (best for ages $0-5$ ) and Epiphyseal fusion (ages $6-25$ ).
Femur: Largest bone; used for height and gender calculations.
Lab Tests: Immunology ( $\text{months old}$ ), Blood pigments (< 10 \text{ years}), Carbon dating ( $100+ \text{ years}$ ).

Rigor Mortis: "Stiffness of death" caused by lack of ATP. Starts $3-4 \text{ hours}$ post-death; full rigor at $12-15 \text{ hours}$ .
Algor Mortis: "Cooling of death." Body cools at a rate of $1.5^\circ\text{F/hr}$ .
Livor Mortis: "Color of death." Blood pooling fixed after $8-12 \text{ hours}$ .
Autopsy Reasons: Find cause/time of death, identification, and evidence collection.
Legal Manners of Death: Natural, Accidental, Homicide, Suicide.

Fingerprint Composition: Produced by dermal papillae; contains salts, water, and oils.
Print Types: Visible, Plastic (molded), and Latent (invisible).
Development Chemicals: Ninhydrin (purple/blue), Iodine Fuming (yellow-brown), Silver Nitrate (grey/black).
Classes: Loops ( $65\%$ ), Whorls ( $30\%$ ), Arches ( $5\%$ ).
AFIS (Automated Fingerprint Identification System): Matches ridge locations; requires $10-16 \text{ points}$ for expert verification.
Handwriting Analysis: Uses exemplars (known samples) to check 12 characteristics (e.g., line quality, slant, diacritics).
Forgery Types: Blind, Stimulated (copied), and Traced.
Obliteration Detection: Uses microscopes, UV light, or Chromatography.