Forensic Science

Forensic Science

The application of science to the criminal and civil laws in the criminal justice system.

What is Anthropology?

The study of bones.

What is Forensic Anthropology?

The study of bones to solve crimes.

What is Criminalistics?

The application of scientific techniques to collect physical evidence.

What are the 4 primary responsibilities of the Crime Scene Investigator?

1. Identify evidence.

2. Collect evidence.

3. Preserve evidence.

4. Maintain chain of custody.

What are Crime Scene Investigators not responsible for?

Solving crimes, identifying suspects, interview witnesses, or follow up on tips.

What is the CSI effect?

When the jury has unrealistic expectations about DNA or other evidence based on what’s been see on TV.

Inductive Reasoning

Starts with specifics and draws a general conclusion based on them.

Deductive Reasoning

Starts with general or broad observation ad draws conclusion based on that generality.

Is an observation objective or subjective?

Objective

Is an inference objective or subjective?

Subjective

What must a suspect have?

Means (the physical ability to commit a crime), Motive (why the crime was committed), Opportunity (the suspect had a chance to commit the crime)

What is testimonial evidence?

Eyewitness accounts

What is physical evidence?

Tangible objects

What is documentary evidence?

Written/auditory/videotaped account

What is demonstrative evidence?

Reconstruction of the crime scene

What is digital evidence?

GPS Data, Cell Phone Tower hits, Vehicle Data

What is genealogical data?

Family trees to identify unknown suspects by comparing to data bases

What is Locard’s Exchange Principle?

“Every contact leaves a trace” or the three way exchange between the scene, victim, and the perpetrator

What is an example of real evidence (physical evidence)?

Bodily fluids, glass fragments, soil, fingerprints, etc.

What is biological evidence?

Evidence where it’s possible to get DNA, like bodily fluids, bones, or body tissues

What is trace evidence?

Evidence that is present in minuscule amounts

What are individual characteristics?

100% unique based on how it’s been used, damaged, or worn

What are class characteristics?

General characteristics of an item like brand, size, color, model, etc.

What is standard evidence?

A known and trusted sample in a data base that is used for comparison.

What is an exemplar?

A known sample collected from the victim/suspect.

What does it mean to get a hit?

A match between standard and exemplar evidence.

What is direct evidence?

Provides proof of a fact.

What is circumstantial evidence?

Requires an explanation/interference

What is the purpose of the Chain of Custody?

To make evidence permissible in court. It tracks every person who has handled it.

What are the guidelines for packaging wet evidence?

Paper bags

What are the guidelines for packing dry evidence?

Plastic

How do you collect hair?

Double-packaged in paper

How do you collect fibers?

Dry, tape-lifted, in plastic

How do you collect paint chips?

Folded in paper, placed in the envelope

How do you collect tools?

Paper/Cardboard

How do you collect evidence on tape?

Non-powdered gloves, plastic

How do you collect glass?

Wrap in paper.

How do you collect arson/fire evidence?

Metal/airtight containers

How do you collect powerders?

Swab and place in envelope or airtight containers

What does a fatal does of fentanyl look like?

A pencil tip’s worth

At the possibility of a fentanyl overdose, administer…

Narcan

What is serology?

The study of bodily fluids.

What is Anthropology?

The study of bones

What is the three criteria that must be used for evidence?

Relevant to the crime, authentic, and accurate

When do you use grid search?

Large open areas in a difficult environment. Everything is searched twice.

When do you use linear search?

When many people are needed.

When do you use a quadrant search?

In an enclosed area or cluttered scene.

When do you use a spiral search?

When you have limited people or a wide open scene.

What is Chromatography?

A technique used to separate pigments in the ink.

What are the four elements to look for when analyzing handwriting?

Form (shape, size, slant), Lines (thickness, type of tool), Arrangement (spacing of words/letters), Content (grammar)

What is a fingerprint?

A pattern of ridges left behind by the human fingerprint.

Why are the fingerprints of identical twins different?

Because the flow of fluid in the womb is different.

What is the first principle of fingerprint identification?

A fingerprint is an individual characteristics so none are identical.

What is the second principle?

A fingerprint remains unchanged during an individual’s lifetime.

What is the third principle?

Fingerprints have general ridge patterns that allow them to be systematically classified.

What type of fingerprint is plastic?

Mud, wax, tar, paint imprint

What type of fingerprint is visible/patent?

Imprint on blood, dirt, ink, grease

What type of fingerprint is latent?

Invisible-must be developed or photographed

What type of fingerprint collection method is dusting?

It’s the most common. Skin secretion sticks to fingerprint powder.

What type of fingerprint collection is superglue fuming?

Superglue is heated to stick to fingerprint glue and some water is added to solidify prints.

AFIS

The automated fingerprint ID system.

What is serology?

The study of blood and biochemical reactions that occur between antigens and antibodies.

What is forensic serology?

Identification and examination of all bodily fluids.

CODIS

Combined DNA Index System - databases of known and unknown DNA profiles from many sources.

What is blood?

Complex mixture of cells, enzymes, proteins, and inorganic substances which is 100% unique to individuals except for identical twins.

What is the percentages of bloods?

Blood is 55% water and 45% solids.

What are the 4 components of blood?

Plasma, erythrocytes, leukocytes, and platelets

Plasma

Liquid portion of blood

Erythrocytes (red blood cells)

Carry hemoglobin and oxygen

Leukocytes (white blood cells)

Fight infection and disease

Platelets

Clotting factors

What is an antigen?

Proteins located on surface of red blood cells.

What is an antibody?

Proteins that recognize and bind to specific antigens to destroy or inactivate a specific antigen.

What type of antigens and antibodies does Type A blood have?

A antigens and B antibodies

What type of antigens and antibodies does Type B blood have?

B antigens and A antibodies

What type of antigens and antibodies does Type AB blood have?

Both A and B antigens and no antibodies

What type of antigens and antibodies does Type O blood have?

Neither A or B antigens and has both A and B antibodies

Determining blood type involves reacting antigen + antibody and seeing if they react with each other.

A positive test is called an agglutination.

What is the Kastle-Meyer test?

It tests if a liquid is blood.

What is precipitin?

Test for if blood is a human’s.

What is the most commonly used chemical today to detect hidden blood?

Luminol or bluestar reagent

What is toxicology?

The study of poisons and their interactions within the body.

What is forensic chemistry?

Drugs outside of the body.

What is a drug?

Natural/synthetic substance that is used to produce physiological or psychological effect.

What law determines which drugs are classified as legal?

USC Controlled Substances Act

What are the 2 criteria used to classify drugs?

Dependence and abuse.

Schedule I

No accepted medical use and high potential for abuse

Schedule II

Drugs, chemicals, or substances with high potential for abuse/dependence

Schedule III

Drugs, chemicals, or substances with moderate to low potential for dependence.

Schedule IV

Drugs, chemicals, or substances with low potential for dependence

Schedule V

Drugs that have small quantities for narcotics and often prescribed for home use

Why do people take stimulants?

Feelings of energy, awareness, speeds up nervous system

What are some side effects?

Absence causes sickness and losses of energy

Why do people take inhalants?

Immediate effects and intense high

What are hallucinogens?

Drugs that alter perception, mood, and thinking

Why do people use hallucinogens?

Curiosity, altered reality, emotional experiences

Why are hallucinogens popular at concerts/festivals?

Belief they enhance music, visuals, and connection

Short-term effects of hallucinogens

Hallucinations, distorted senses, panic, confusion

Long-term risks of hallucinogens

Flashbacks, anxiety, depression, psychosis