Forensic Science Overview and Applications

Forensic Science and Criminalistics

• Forensic Science: The application of science to legal matters
• Criminalistics: The application of scientific methods to the investigation of crimes

The CSI Effect

• Overestimation of forensic science capabilities
• Increased expectations for forensic evidence in court cases

The Penny Parker Case

• Forensic Technique: DNA profiling
• Solved by linking DNA from the crime scene to the suspect

Civil vs. Criminal Court

• Civil Court: Focuses on disputes between individuals or organizations
• Criminal Court: Deals with crimes against the state or society

Expert Witness Qualifications

• Demonstrated expertise in a particular field
• Acceptance by the court as knowledgeable and reliable

Criminalist Duties

DNA Analyst

• Identifies and analyzes biological evidence
• Provides DNA profiles for comparison

Toxicology Analyst

• Examines bodily fluids and tissues for the presence of drugs or poisons
• Determines the role of substances in death or injury

Alcohol Analyst

• Analyzes blood or breath samples to determine alcohol content
• Provides evidence for DUI investigations

Trace Analyst

• Examines microscopic evidence such as fibers, hair, or paint
• Links suspects and crime scenes based on trace material transfer

Firearms Analyst

• Examines firearms and ammunition
• Determines the origin and history of firearms used in crimes

Educational Requirements for Crime Lab Work

• Bachelor's degree in science related fields
• Specialized training for specific roles

Crime Lab Issues

• Backlog of cases
• Lack of funding and resources
• Pressure for faster results

How to Solve Crime

• Forensic Science: Application of science to solve crimes
• Criminalistics: Scientific methods for crime investigation
• Key: Locard Exchange Principle - Every contact leaves a trace
• Forensic Diamond: Interconnection between scene, evidence, suspect, and victim
• Evidence Association: Linking evidence to a person or crime scene

Evidence Types

• Real Evidence: Physical objects related to the crime
• Demonstrated Evidence: Items created for the purpose of illustration or explanation

The Basis of Evidence

• Transfer: Movement of evidence from one location to another
• Persistence: Ability of evidence to remain at a location
• Conditions Affecting Transfer: Time, pressure, and type of material
• Classifying Evidence: Identity (class characteristic), Class (common to many), Individualization (unique to a single source)

Death and Crime Scene Investigation

• Manner of Death: How the death occurred (natural, homicide, suicide, accident)
• Cause of Death: The specific injury or disease that led to death
• Rigor Mortis: Stiffening of muscles after death
• Livor Mortis: Pooling of blood in the body after death
• Algor Mortis: Cooling of the body after death

Estimating Time of Death

• Most Accurate: Scientific methods (temperature, potassium levels)
• Other Markers: Environmental factors, daily activities, and microbiome

Yosemite Murder

• Applying Forensic Diamond: Identifying links between scenes, suspects, victims, and evidence

• Crime Scenes: Little Green Cabin, Lake Don Pedro, Hotel, Rental Car

• Evidence*

• Evidence: Anything that helps prove or disprove a fact in court

• Trier-of-fact: Judge or jury who decides the facts of a case

• Determination: Establishing the truth based on evidence presented

• Types: Real evidence, Demonstrated evidence

• Locard Exchange Principle: Every contact leave a trace

• Basis of Evidence: Transfer and persistence

• Classifying Evidence: Identity, Class, Individualization

Forensic Science Overview

• Forensic Science applies scientific principles to legal proceedings, assisting justice systems.
• Criminalistics analyzes and interprets crime scene evidence to reconstruct events, focusing on individualization.
• The CSI Effect: Media portrays unrealistic expectations of forensic science, potentially influencing jury expectations.
• DNA Analyst analyzes biological samples (blood, hair, saliva) to identify individuals and link them to crimes.
• Toxicologist analyzes bodily fluids for drugs, narcotics, and alcohol, providing information about intoxication and other potential causes of death or incapacitation.
• Trace Analyst analyzes microscopic evidence like fibers, paints, and soils to link suspects, victims, and crime scenes.
• Firearms Analyst examines bullets and cartridge cases, identifying firearms, reconstructing shooting incidents, and analyzing gunshot residue.
• Expert Witness: Individuals with specialized knowledge, recognized by a court, who provide impartial expert opinions based on their expertise.
• Qualifications for Expert Witnesses:
  • Demonstrated expertise in specific scientific methodology and knowledge of its limitations.
  • Familiarity with relevant scientific literature.
  • Ability to clearly articulate their opinions and supporting evidence.
  • Independence as an expert witness.
  • Willingness to be cross-examined and challenged by opposing counsel.

Careers in Forensic Science

• Criminalist requires a bachelor's degree in a scientific field.
• DNA Analyst requires a bachelor's degree with additional biology and lab courses.
• Crime Labs face challenges with standardizing procedures across different labs, ensuring consistent handling and analysis of evidence.

Solving Crimes

• Forensic Science utilizes scientific principles to resolve legal disputes.
• Criminalistics focuses on individualization, linking suspects and victims to the crime scene through evidence.
• Key to Forensic Science: Forensic associations prove the connection between individuals, objects, and locations.
• Locard Exchange Principle: Every contact leaves a trace, meaning any interaction results in the transfer of material.
• "Forensic Diamond": A framework for forensic analysis connecting the victim, suspect, crime scene, and evidence.
• Forensic Associations: Evidence like animal hairs, building materials, chemical analysis, liquids, and stains can link individuals to the crime.

Death Investigation

• Manner of Death: Explains how death occurred (e.g., suicide, homicide, natural, accident).
• Cause of Death: Identifies what caused death (e.g., gunshot wound, heart attack).
• Rigor Mortis: Muscle stiffness after death.
• Livor Mortis: Blood pooling in the lowest part of the body due to gravity, indicating body position after death.
• Algor Mortis: Body cooling after death. The liver is the most accurate place to measure temperature for time of death estimation.
• Order of Shut Down After Death: Respiratory system, circulatory system, central nervous system, cellular metabolic pathway.
• Stomach Content: Indicates when the deceased last ate, providing time frame for death estimation.
• Vitreous Potassium: Potassium levels in eye fluids increase after death, acting as a biological clock for time of death estimation.
• Autolysis: Breakdown of body tissues by internal digestive enzymes.
• Putrefaction: Decomposition of proteins due to bacteria and fungi.
• Environmental Clues: Uncollected mail, food on stove, unfinished activities, clothing type can indicate time since death.
• Habitual Activities: Walking patterns, sleep schedules, eating habits can be useful in time of death calculations.

Explore the fascinating world of forensic science and criminalistics through this quiz. Delve into key concepts like the CSI Effect, the Penny Parker case, and the roles of expert witnesses. Test your knowledge on the differences between civil and criminal courts and the responsibilities of DNA and toxicology analysts.