Forensics Midterm studyguide.

Forensic Science

Study and Application of science to matters of law.

accurate through information to all levels of criminal justice

• examiners FIND DOCUMENT AND INTERPRET

Deductive Reasoning

clues that help you work backwards to solve crime case

It is important to separate witnesses at the crime scene to…

prevent the witnesses from talking to each other

Correct collection of evidence requires

• documenting the location where the evidence was found

• correct packaging of evidence

• maintaining proper chain of custody

A crime-scene sketch should include…

• a scale of distance

• date and location of crime scene

• north heading on the diagram

yet the scene sketch does not need to include…

the type of search pattern used to collet the evidence

the goal of crime scene investigation is to

• recognize evidence at the scene of the crime

• document evidence

• collect evidence

direct evidence

includes first hand observations such as eyewitness accounts

circumstantial evidence

evidence that can be used to imply a face but does not directly prove it.

trace evidence

a type of circumstantial evidence

class evidence

narrows an identity to a group of people or things

the crime scene investigation team is made up of

legal and scientific professionals who work together to solve a crime

first person to arrive at a crime scene usually is

police officers

all evidence needs to be packaged properly, sealed, and labeled. Charred debris remains in

airtight, unbreakable containers.

if hair is found at a scene, what type of evidence is this?

trace evidence

a knife was found that belonged to a suspect in a burglary. what type of evidnece is thisencircum

circumstantial evidence

first hand observations by eyewitnesses are

direct evidence

when photographing the crime scene, one must remember to

• use a ruler to show the scale of evidence

• take wide-angle and close-up photos

• take pictures of the scene and surroundings.

a blood soaked piece of evidence

must be dried from the packaging to prevent mold and mildew.

Notes at the crime scene have…

detailed written descriptions of the scene, location of the items, time a item of physical evidence was discovered and by whom

rigor mortis

is due to the loss of ATP in muscle tissue. Muscles no longer function normally and begin to contract and stiffen.

algor mortis

is the loss of heat by a body beginning about an hour after death. the body loses heat 1-1 ½ degrees until the body reaches the environment temp.

livor mortis

is the settling of blood in areas of the body closest to the ground. begins immediately after death and up to 12 hours. discoloration is permanent after 8 hours.

factors that affect rigor mortis are…

• ambient temperatures

• weight of the body

• if there are clothes on the body

if undigested stomach contents are present…

death had occured 0-2 hours after the last meal

the cause of death is

the “reason” or an event that leads to a persons death.

the mechanism of death is

the underlying cause or the physiological reason for a person’s death.

the five possible manners of death

• accidental

• suicide

• homicide

• natural

• undefined

the death occurred 12 hours after meal

if the small intestine is empty and wastes are found in large intestines

who was JonBenet Ramsey

a six-year-old rising star in the beauty pageant world when she was found brutally murdered in the basement of her home on December 26 1996

In the JonBenet case the officer pulled up in…

a customary black and white police cruiser (an obvious mistake because an unmarked car or undercover officers should have been the ones to respond to the kidnapping call)

Good police procedure in the JonBenet case would have been…

• empty the house immediately

• take the inhabitants to the police station

• post a patrol officer inside the front door

• allow entry to authorized personnel only.

Locard’s principle of exchange

when a person comes into contact with an object or person, a transfer of physical evidence can occur.

trace evidence

materials that are transferred from one person or object to another

identification of a blood sample

class evidence

shoe print is an example of

physical evidence

hair sample is an example of

biological evidence

fingerprints are an example of

physical evidence

soil samples are an example of

physical evidence

a special scientists who might examine insects found on a decaying corpse is called

entomologist

a bullet casing from a .38 caliber gun is an example of

class evidence

carpet fibers removed from a crime scene is an example of

class evidence

bodies remain rigid for up to… and reverse themselves in the same exact order

12 hours

discoloration from liver mortis is permanent after

8 hours

cold temperatures

decrease the decomposition process

if a victim has clothes on or is overweight, then rigor mortis is….

increased

a druggist fold consists of carefully folded paper into thirds to produce a closed container that keeps …. from falling out

specimen

the dermal papillae are a boundary of cells that…

separate the outer portion of the skin and the inner skin.

the shape of the dermal papillae determines…

the form and the pattern of the ridges on the surface of the skin.

to obscure ones fingerprints…

an injury or surgery must reach deeply enough into the skin to damage the dermal papillae

the AFIS scans fingerprints and coverts them…

into digital images that contain data on the relative location and orientation of ridge characteristics.

the AFIS system records the point where they branch into…

2 ridges and the relative position and orientation of each characteristic.

the final step in fingerprint identification is…

visual comparison of the prints in question by a trained examiner.

AFIS

the database used to find matches for fingerprint samples from a crime scene

loop

the most common type of fingerprint

7

radial loop left hand

enter from right, leaves on right

radial loop on right thumb

enters from left, leaves on left

what is this picture

short ridge

what is this picture

fork

what is this picture

eye

what is this picture

ending ridge

if the dermal papillae doesn’t change its shape throughout its lifetime, then…

ridge patterns of fingerprints also do not change

the 3 categories of fingerprints

• loops

• whorls

• arches

identify ridge characteristic

crossover

identify ridge characteristic

core

identify ridge characteristic

island

identify ridge characteristic

delta

what is this fingerprint

plain whorl

what is this fingerprint

central pocket whorl

two things a forensic examiner looks for on a fingerprint are the presence of a

core and delta

every individual including identical twins has a unique fingerprint due to unique ridge patterns called

minutiae

have there been any two people found who have identical fingerprints?

none to date

ninhydrin is used on a latent print to detect

amino acids

what chemical treatment produces a white-appearing latent print

super glue fuming

the region of hair located outside of the medulla containing granules of pigment is called

the cortex

the type of protein that makes up hair is

keratin

all mammals have hair, its purpose is to

regulate body temperature to keep the body warm.

microscopic characteristics include

• pattern of medulla

• pigmentation of the cortex

• types of scales on the cuticle

if hair is forcibly removed from victim, the entire _____ may be present

follicular tag

hair consists of two parts

follicle and shaft

hair shaft is made up of 3 layers

• inner medulla

• cortex

• outer cuticle

the cuticle is

the transparent outer layer of the hair shaft

in humans the cortex is

the largest part of the hair shaft

central core of hair fiber

the medulla

In animals, the cortex is

the smallest part of the hair shaft

hair proceeds through ____ as it develops

3 stages

the cuticle of human hair is described and most commonly seen as

imbricate scale

whenever 2 objects are in contacts, some transfer will happen knows as

Locard’s exchange principle

which part of hair can be analyzed for DNA

the root can be analyzed

in humans the medulla is the

smallest part of the hair shaft

in animals the medulla is the

largest part of the hair shaft

the period of active hair growth is

anagen stage

the period of dormant hair growth is

telogen stage

the period of growing and changing hair is

catagen stage

cuticle scales of the hair always point towards the

tip of the hair

during hair coloring or bleaching, the portion of the hair shaft that absorbes the color is

the cuticle

head hairs of a person are not….

identical

DNA can not be extracted from…

the cells in the hair shaft

unbroken line of the medulla is called

continuous

when viewing hair shaft under high power of micrscope,

the magnification of the hair is 100x

the hair growth, the anagen phase may last up to

6 years