Forensics Final Study Guide

How are crime scenes documented?

Taking notes, sketching, photographing, videotaping

Why is it so important for investigators to secure a crime scene?

Environmental factors can quickly destroy physical cues, bystanders or suspects can alter the scene.

What type of search is the most effective in large open areas, such as fields?

Grid Method

What happens to evidence once it has been found?

Documented, collected, secured in custody

How much evidence should be collected at a crime scene?

As much as possible and practical

Authentication in evidence collection refers to?

a rule of evidence that it must be sufficient enough to support a finding

Videotaping for documentation purposes at a crime scene is an acceptable substitute for…

sketching

Why should disposable gloves be worn while handling and collecting evidence at a scene?

to prevent contamination

List details of a rough crime scene sketch.

hand-drawn, non-scaled, pencil-drawn document created at a crime scene to capture the layout and accurate measurements of evidence

What is the first task of the first responders to a crime scene?

ensure safety and stabilize the situation by identifying threats, providing emergency care to victims

Define fingerprints

friction ridge skin pattern found on fingers, palms, toes, soles of feet, composed of ridges (hills) and furrows (valleys)

Define plastic prints

indentation in soft material such as butter, putty, or tar

Define latent prints

requires processing to make visible and suitable for analysis ex. weapons, documents, adhesive materials

Define arch

an arch is formed by ridges entering from one side of the print, rising slightly and exiting on the opposite side

Define loop

a loop must have one or more ridges that enter from one side of the print, recurve and exit the same side

Define whorl

one or more cores, at least two deltas

Define ulnar loop

When looking at the right hand, the ulnar loop opens towards the pinky

Define radial loop

When looking at the right hand, the radial loop opens towards the thumb

Define accidental fingerprints

All other prints, combination prints, prints that do not follow other patterns

Define core

the approximate center of a fingerprint pattern

What is AFIS?

Automated Fingerprint Identification System

Is footwear evidence considered class or individual evidence?

Footwear evidence starts as class but can become individual after being worn or having unique damage

What is the best casting material for footprints and tire impressions?

Dental stone

What is the outer part of the tooth called? Which part contains the DNA?

crown, pulp

When was the first recorded use of dentition for identification purposes?

66 AD, when Agrippina ordered Lollia’s teeth as proof of her death

What is the importance of Doyle v. Texas, 1952?

it was the first reported U.S. case to admit bite mark evidence to secure a criminal conviction

How many adult teeth do you have?

32

How are bite mark patterns always shaped?

like two half moons

Bitemark photos should include what in the photograph?

an official reference scale, clear documentation of victim, case number, & date

What is “elimination footwear”?

test impressions taken from the shoes of first responders, residents, or authorized personnel at a crime scene

What types of items should you look for on the bottom of a shoe for it to be individual evidence?

nicks, cuts, scratches, gouges, or uneven wear patterns

Define cortex

immediate layer of hair shaft, surrounding medulla

Define medullary index

the ratio of the diameter of the medulla to the total diameter of the hair shaft, used partially to distinguish human hair from animal hair

Define shaft

the portion of the hair that projects from the skins surface, extending from the follicle to the tip

Define medulla

the innermost, central core layer of a hair shaft, often composed of vacuoles and air-filled cells

Define cuticle

the outermost, protective layer of the hair shaft, consisting of flattened, overlapping, transparent cells called scales that always point toward the top

Define hair root

the bulbous, proximal portion of a hair shaft located within the hair follicle beneath the skins surface

What is the medullary index for human hair? Animal?

Human hair is less than 1/3 or 0.33, Animal hair is more than ½ or 0.5

Define synthetic fibers

manufactured, polymer-based fibers

Define natural fibers

threadlike material derived from plant, animal, minerals

Give examples of synthetic and natural fibers

Synthetic - nylon, polyester, acrylic

Natural - cotton, wool

What is the most common type of plant fiber?

Cotton

List the human blood groups.

A, B, AB, O (and positive and negative)

What type of blood spatter arises when blood under pressure strikes a target?

Arterial spurting

What is the angle at which a blood droplet strikes a surface?

angle of impact

What must be present in order to confirm a pattern is an arterial bloodstain pattern?

a projected, high volume blood pattern with distinct pressure fluctuations, often creating surge or wave-like characteristics

The universal blood donor for the ABO system is?

Type O

What are antibodies in terms of blood analysis?

proteins made by the immune system to fight foreign substances like viruses, bacteria or toxins

What determines what type of blood a patient can recieve?

Antigens

What are antigens in terms of blood analysis?

protein or sugar markers on RBC or foreign substances that trigger an immune response

define wipe

non-blood bearing object moves through a wet blood stain, altering the appearance of the original stain

define transfer pattern

pattern created when a wet, bloody object comes into contact with a target surface, leaving a pattern, that has the features of the object making it useful in identifying the object

define cast-off

blood that has been thrown from a secondary object (weapon/hand) onto a target other than impact site

define contact stain

blood stains caused by contact between a wet blood-bearing surface and a second surface which may or may not have blood on it

define swipe

wet blood is transferred to a surface which did not have blood on it

what is the scientific name for white blood cell? red blood cell?

leukocytes, erythrocytes

what is the formula used to calculate angle of impact

sin -1 (width/length)

what are small drops of blood that break off from the parent droplet when it strikes a target surface?

satellite spatter

what is the method used for determine point of origin for blood stains?

area of convergence

what is the legal limit of BAC for consumers over 21?

0.08 or higher

what was the most common types of poison used in the toxicology cases studied?

pharmaceutical drugs

who was dr. death

neurosurgeon who killed 33/38 patients

who was jim jones

infamous cult leader, jones town

alcohol is eliminated from the body chemically unchanged in

breath, urine, and preservation