Forensics Semester One study guide

observation

the process of gathering information about events or processes, using the five senses.

prediction

an educated guess about a future event, based on observation and experience.

qualitative observation

an observation that is descriptive and uses the 5 senses

quantitative observation

involves numbers or amounts obtained by counting or measuring.

inference

A conclusion reached on the basis of evidence and reasoning

forensics

the study and application of science to matters of law

forensic pathology

branch of forensics that involves medical doctors and performing autopsies

forensic odontology

Branch of forensics that involves a dentist helping identify a body with dental records

forensic computer science

Branch of forensics that involves tracking down hackers

forensic toxicology

branch of forensics that examines body fluids and organs for the presence of drugs and poisons

forensic entomology

branch of forensics that involves insects

forensic engineering

branch of forensics that involves investigating the structural integrity of buildings, structures, and bridges.

Forensic anthropology

Branch of forensics that involves studying bones/human remains

Biology unit

Unit in forensics that examines blood samples, bodily fluids, botanical samples, hair, and fiber samples.

physical science unit

unit in forensics that identifies and compares physical evidence such as drugs, soil, minerals, and trace evidence

forensic serology

branch of forensics that involves the identification of blood and other body fluids

Forensic Psychiatry and Psychology

branch of forensics that involves profiling criminal cases

firearms unit

unit of forensics that investigates discharged bullets, cartridge cases, and shotgun shells.

Document Examination Unit

unit in forensics that provides handwriting analysis, ink and paper analysis, and confirms the authenticity of documents.

Photography Unit

unit in forensics that is responsible for recording and examining physical evidence and evidence displays in the courtroom.

Fingerprint Unit

forensics unit that processes and examines crime scene and evidence for latent fingerprints.

Polygraph Unit

conducts polygraph (lie detector) tests

Voiceprint Analysis Unit

attempts to tie a recorded voice to a particular suspect

Evidence-Collection Unit

Sends specially trained personnel to collect and preserve physical evidence. They are responsible for the chain-of-custody process.

FBI

Federal Bureau of Investigation

DEA

Drug Enforcement Administration

ATF

Bureau of Alcohol, Tobacco, and Firearms

USPIS

United States Postal Inspection Service

Misdemeanor

minor crime such as theft, minor assault and battery, or possession of a small amount of illegal drugs.

Felony

major crime such as murder, rape, armed robbery, serious assault, dealing illegal drugs, fraud, auto theft, or forgery

4th amendment

search and seizure

5th amendment

Grand Jury, Double Jeopardy, Self-Incrimination, Due Process

6th amendment

Criminal prosecutions, right to a speedy trial by an impartial jury

7th amendment

Common Law Suits - right to a trial by jury

8th amendment

No Cruel and Unusual Punishment or excessive bail

Locard's Exchange Principle

Whenever 2 objects come in contact with one another, a cross-transfer of physical evidence can occur.

Direct evidence

a first hand observation

Circumstantial evidence

indirect evidence that can be used to imply a fact but doesn't directly prove it. The more circumstantial evidence there is, the more credible it becomes.

Physical evidence

synthetic fibers, weapons, bullets, paint chips, documents, imprints and prints (shoe, tires, etc.), tool marks, soil, drugs, etc.

Biological evidence

body or body parts, body fluids, hair, teeth, leaves, natural fibers, feathers, wood

Trace evidence

small, but measurable amounts of physical or biological material found at the crime scene. Ex. A strand of hair, a fingerprint, DNA, a drop of blood, pollen, gunshot residue

Class evidence

narrows the evidence down to a group ex. Blood type

individual evidence

points to a single person or thing ex. DNA, fingerprints, handwriting, etc.

Secure the Scene

arrest a suspect (if possible), preserve evidence & prevent people from contaminating the crime scene

Separate the Witnesses

Witnesses cannot talk to each other because they could influence each other's memories or make up a story together.

Scan the Scene

decide where photos should be taken, decide what is the primary and secondary crime scenes are.

Primary crime scene

where the crime actually took place

Secondary crime scene

related to the crime but is not where the actual crime took place

See the Scene

The Photography Unit takes photos of the overall area and close up photos of the evidence with and without a measuring ruler.

Sketch the Scene

an accurate rough sketch must be made of the crime scene. (know what needs to be included)

Search for Evidence

an organized search for evidence should be made and evidence marked, photographed, and sketched.

Strip or line search

used outdoors and when there is a large area to be covered.

Pie or wheel pattern search

used outdoors in fields, desert, or other open areas, involves dividing the search area into sections of a wheel, starting in the center and radiating out.

Spiral search

often used for outdoor searches, examines the area in an ever widening circle from core to perimeter. It is used to find specific items, ex. shell casings

Grid search

used for outdoor searches or intricate interior sites. It is like a strip/line search but also divides the search lanes perpendicularly.

Quadrant or zone search

divides the search area into smaller sections that can be searched in smaller groups

Elevation Zone search

used indoors, starts at the floor and goes up, helps prevent contamination of the crime scene, good when blood spatter is present.

Securing & Collecting Evidence

all evidence must be properly packaged, sealed, and labeled.

Analyze the Evidence

A forensic lab processes all evidence collected from the crime scene.

Crime Scene Reconstruction

Allows the detectives to form a hypothesis and timeline of the crime

Follicle

club-shape structure in the skin that produces hair

papilla

a network of blood vessels that supply nutrients to the hair.

shaft

part of hair that is made of keratin and makes the hair strong and flexible

Cuticle

outside coating of the hair shaft that is comprised of overlapping scales

cortex

middle layer of the hair shaft

medulla

central core of the hair

Anagen stage

Period of active growth. Cells around the follicle are rapidly dividing & depositing materials. Lasts about 1000 days. About 85% of all human hair is in this stage

Catagen stage

Transitional stage. Lasts a few weeks. Hair growth slows. 2% of all hair growth & development

Telogen stage

Final resting stage. Follicle is dormant. Hair easily lost. 12% of all hairs are in this stage. Lasts a few months.

affect of bleaching hair

removes pigment granules; gives yellowish tint, makes hair brittle

affects of dyeing hair

changes color of the hair shaft; cuticle & cortex both take the dye color

european hair

generally straight or wavy; color may be blond, red, brown, or black

asian hair

straight; black hair, continuous medulla

african hair

kinky, curly, or coiled; dark

Assemblages

groups of plants usually dominated by one species

Pollen

the male reproductive structure of a seed plant

palynology

the study of pollen

how non-seed plants reproduce

by dispersing spores

how seed plants reproduce

produce cones or flowers that make pollen to disperse male gametes.

Gymnosperms

oldest seed plants, found in cones not fruit

angiosperms

flowering plants that produce seed within a fruit

Cross-Pollination

involves 2 distinct plants, produces more pollen than self-pollinating plants, produce large amounts of pollen, most flowering plants use cross-pollination

Self-pollination

the transfer of pollen from an anther to a stigma within the same flower ex. pea plants

Spores

asexually reproductive structures produced by a variety of organisms, including algae, fungi, & plants

Bacterial endospores

not a reproductive structure, produced to protect bacteria in unfavorable conditions.

Diatoms

single celled or colonial organisms that are found in fresh water, salt water, and mud.

Eggs

small, cream-colored objects/things laid on or near orifices (mouth, nose, ears, etc.)

Maggots

larval stage

Maggot mass

large group of maggots that generate a lot of heat

Migrating maggots

3rd instar maggots migrate away from the body and burrow into the soil to begin to form puparia

Puparia

dormant stage of an insect

fresh decay occurs...

1-2 days after death

bloat (autolysis) occurs...

2-6 days after death

active decay occurs...

5-11 days after death

post decay (maggots move away) occurs...

10-25 days after death

dry (skeletonized) decay occurs...

25+ days after death

function of a microscope

to enlarge the image of a specimen so that it is easier to see the details

Compound Light Microscope

uses visible light and lenses, 1000x magnification, Cheap and simple, Low resolution

Dissection (Stereo) Microscope

uses visible light and lenses, 3-D images, 100x magnification, relatively cheap, limited resolution

Scanning Electron Microscope

uses electrons and a computer to form the images, uses whole, dead, gold stained specimens, 250,000x magnification, very detailed images, complex specimen preparation, expensive equipment