Forensic Science Midterm Flashcards

Questions and Answers

What is forensics?

The study of DNA and human evidence in order to answer legal questions.

How do perception, emotions, familiarity with a scenario, and other factors affect observation skills and eyewitness accounts?

Our brains unconsciously filter out what is/isn't important. You must make a conscious effort to pay attention to everything systematically.

What is deductive reasoning?

Deriving the consequences from the facts using a series of logical steps.

What is the Innocence Project?

An organization that works to reexamine post-conviction cases to provide conclusive proof of guilt/innocence. Signup and view all the answers

What is a perpetrator?

A perpetrator is an individual who commits a crime of any type. Signup and view all the answers

What is Locard's exchange principle?

When a person comes in contact with an object/another person, a cross-transfer of physical evidence can occur. Signup and view all the answers

Distinguish between class and individual evidence.

Class evidence narrows an identity down to a group of people/things. Individual evidence narrows an identity to a single person or thing. Signup and view all the answers

Distinguish between direct and circumstantial evidence.

Direct evidence includes firsthand observations, such as eyewitness accounts or videos. Circumstantial evidence is indirect evidence that can imply a fact but not directly prove it. Signup and view all the answers

Identify and describe the roles of personnel present at a crime scene.

Police are the first responders. CSI document and collect evidence. Coroners determine the cause of death. Signup and view all the answers

What are the seven steps of crime scene investigation?

<ol> <li>Secure the scene, 2) Separate witnesses, 3) Scan, 4) See the scene, 5) Sketch, 6) Search for evidence, 7) Secure/collect evidence.</li> </ol> Signup and view all the answers

What is a bindle?

A folded paper used to hold trace evidence. Signup and view all the answers

What are the proper steps to sketching a crime scene?

First a rough sketch is drawn. Each object picture is measured, labeled, and scaled. Signup and view all the answers

What is crime scene reconstruction?

A hypothesis of the sequence of events from before the crime was committed through its commission. Signup and view all the answers

What are examples of staged crime scenes?

Examples could include arson, suicide/murder, and burglary. Signup and view all the answers

What are examples of mishandling a crime scene?

Mislabeling or poorly collecting evidence. Not recording everything, even things that seem insignificant. Signup and view all the answers

Distinguish between class and individual evidence that can be obtained from hair.

Class evidence can lead to a group of people with the same hair type. Individual evidence is when a hair follicle is present. Signup and view all the answers

What are the four functions of hair?

<ol> <li>Regulates body temperature, 2) Decreases friction, 3) Protects against sunlight, 4) Acts as a sense organ.</li> </ol> Signup and view all the answers

What is the structure of hair?

The follicle is the base of the hair and contains DNA. The shaft is made of keratin, the cuticle is a transparent outer layer, the cortex is the part with pigment, and the medulla is the center. Signup and view all the answers

What is melanin?

A protein pigment found in epidermal cells, protecting skin against radiation from the sun. Signup and view all the answers

What are names and appearances of the five medulla patterns?

Continuous, Interrupted, Fragmented, Solid, None. Signup and view all the answers

What is neutron activation analysis (NAA)?

NAA looks for 14 different elements and the likelihood that the composition of 9 elements is the same as yours is 1 in a million. Signup and view all the answers

What happens in each of the hair growth stages?

<ol> <li>Anagen Stage = active growth period, 2) Catagen Stage = transition time, 3) Telogen Stage = final stage where hair falls out.</li> </ol> Signup and view all the answers

What are imbricate, spinous, and coronal cuticles?

Coronal: stacked crowns, Imbricate: flattened overlapping scales, Spinous: resembles petals. Signup and view all the answers

What is the rate of hair growth and how can it be used in forensics?

Hair grows at a rate of 1.3 cm per month. Signup and view all the answers

How do fingerprints form?

Fingerprints are formed when a tiny developing baby touches its surroundings, creating friction ridges. Signup and view all the answers

Describe and identify the relative occurrence of loops, arches, and whorls.

Loops are found in 65%, whorls in 30%, and arches in 5% of the population. Signup and view all the answers

Define and identify cores, deltas, and ridge counts.

The core is the center, delta is a triangular region near the loop, and ridge count is an imaginary line from core to delta. Signup and view all the answers

Distinguish between plain whorl, central pocket loop whorl, and double loop whorl.

Plain whorl (24%), Central Pocket Loop (2%), Double Loop (4%). Signup and view all the answers

Distinguish between plain arch and tented arch.

Plain arch (4%) and Tented arch (1%). Signup and view all the answers

How many minutiae similarities are needed to match a suspect?

You need at least 12 minutiae similarities to match a suspect. Signup and view all the answers

Distinguish between patent, plastic, and latent fingerprints.

Patent prints are visible, latent prints are hidden, and plastic prints are 3D. Signup and view all the answers

What is IAFIS (Automated Fingerprint Identification System)?

Fingerprints are digitized, compared to all prints in the system, and verified by a human. Signup and view all the answers

How can blood provide both class and individual evidence?

Blood type is class evidence, DNA profiling from blood is individual evidence. Signup and view all the answers

What are plasma, platelets, red blood cells, and white blood cells?

Plasma is the liquid part. Platelets aid in clotting. Red Blood Cells carry oxygen. White Blood Cells fight disease. Signup and view all the answers

How is blood type compatibility determined?

If you have the 'A' antigen, you produce 'B' antibodies, and vice versa. Signup and view all the answers

Which blood types are the universal recipient and universal donor?

Type O- is the Universal Donor, and Type AB+ is the Universal Recipient. Signup and view all the answers

What is agglutination?

The clumping of molecules or cells caused by antigen-antibody reaction. Signup and view all the answers

What is the difference between a round drop of blood vs. drops with tails or satellites?

Blood on flat surfaces appears round. Satellites occur from an angled drop. Signup and view all the answers

What is the effect of height on blood spatter size, satellites, and spikes?

Higher drops can cause a different size drop; the higher the height, the bigger the drop. Signup and view all the answers

How can the angle of impact be calculated?

Using the formula: sin-1(W/L). Signup and view all the answers

What is cohesion?

An attraction between molecules of the same substance. Signup and view all the answers

What is toxicology?

The study of drugs and poisons, and their interactions with or effects on the body. Signup and view all the answers

Study Notes

Forensic Science Overview

Forensics is the study of DNA and human evidence used to answer legal questions.
The Innocence Project reexamines post-conviction cases to prove guilt or innocence.

Observation and Evidence Collection

Observation can be influenced by perception, emotions, and familiarity, leading to selective memory.
Improvements in observation skills require conscious effort and systematic attention to detail.
Class evidence narrows identity to a group, while individual evidence points to a specific person or thing.

Evidence Types

Direct evidence consists of firsthand observations like eyewitness accounts; circumstantial evidence relies on implications rather than direct proof.
Forensic evidence includes Locard's exchange principle, indicating that physical evidence transfers when a person interacts with objects.

Crime Scene Protocol

Key personnel include police, crime scene investigators (CSIs), medical examiners, and detectives; each has distinct responsibilities in evidence collection.
Essential steps in crime scene investigation include securing the scene, separating witnesses, and meticulously searching for evidence.

Hair Evidence

Hair characteristics include macroscopic traits (length, color) and microscopic features (medulla pattern, scale types).
Mitochondrial DNA (mtDNA) is unique for tracing maternal lineage and can be crucial in forensic analysis.
Hair grows at an average rate of 1.3 cm per month, aiding in the estimation of time since deposition.

Fingerprint Analysis

Fingerprints develop in the womb through friction ridges and show unique patterns, categorized into loops, whorls, and arches, with loops being the most common.
Minutiae points, such as cores and deltas, are critical for matching fingerprints, requiring a minimum of 12 similarities for a conclusive match.
IAFIS facilitates the digital scanning and comparison of fingerprints across a vast database.

Blood Evidence

Blood provides both class (blood type) and individual evidence (DNA profiling).
Types of blood cells: plasma (liquid component), platelets (clotting), red blood cells (oxygen transport), and white blood cells (immune response).
Blood typing tests identify blood types based on antigen-antibody reactions, with Type O- as the universal donor and AB+ the universal recipient.

Blood Spatter Analysis

Blood spatter patterns can reveal the mechanism of injury and the position of the victim.
Cohesion causes blood to maintain its shape when splattered; droplet size indicates the height from which blood fell.
Tests like Luminol and Kastle-Meyer confirm the presence of blood stains.

Toxicology

Toxicology assesses the impact of drugs and poisons on the body, categorizing substances into narcotics, depressants, stimulants, hallucinogens, and anabolic steroids.

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Description

These flashcards cover essential concepts in forensic science, including the basics of forensics and the factors affecting observation skills. Perfect for midterm preparation, this quiz enhances your understanding of how evidence is analyzed in legal contexts.