ultimate forensics final review

Forensics

The study and application of science to matters of law

Evidence

Proof that shows what happened.

Criminalistics

The scientific examination of physical evidence for legal purposes

Criminology

Includes the psychological angle, studying the crime scene for motive, traits, and behavior that will help interpret the evidence.

What is needed to solve a crime?

Evidence, eye witness testimony, and forensic tools/experts

Sir Arthur Conan Doyle

Author of Sherlock Holmes who demonstrated principles of serology, fingerprinting, firearm identification, and document examination.

Mathieu Orfila

Father of forensic toxicology (first use of toxicology regards Marie and Charles Lefarge)

Francis Galton

Studied fingerprints and developed a method of classifying them for filing (first used when a man killed Hiller and left his fingerprints on the window that he came from)

Leone Lattes

Devised a simple procedure for determining the blood group of a dried blood stain

Calvin Goddard

First used the comparison microscope to determine whether or not a gun fired a bullet

Albert Osborn

Developed the fundamental principles of document examination.

Alphonse Bertillon

First scientific system of personal identification by taking a series of body measurements to distinguish one individual from another (called anthropometry)

Edmond Locard

The father of criminalistics; Locard's exchange principle (every contact leaves a trace; cross transfer of evidence occurs)

National Level Crime Labs

FBI, ATF, DEA

FBI (Department of Justice)

Largest crime lab in the world and has broad investigative powers

DEA (Drug Enforcement Agency)

Responsible for the analysis of drugs seized in violation of laws regulating the production, sale, and transportation of drugs

ATF (Bureau of Alcohol, Tobacco, Firearms, and Explosives)

Works in conjunction with the Gun Control Act and Organized Crime Control

J. Edgar Hoover

Sets up the first national Crime Lab in the USA and L.A. crime lab is now the oldest in the U.S.

State Level

Most state governments maintain a lab to service state and local law enforcement. Some larger cities maintain their own crime lab, usually under the direction of local police dept.

Local Level

Local labs provide services to county and municipal agencies; independent & financed by local government.

Functions of a Forensic Scientist

Analyze, testify, train

Analysis of Physical Evidence

Applies the principles and techniques of the physical and natural sciences to the analysis of evidence.

Provision of Expert Testimony

May be required to testify with respect to methods and conclusions at a trial or hearing.

Furnish Training

Train law enforcement in the proper recognition, collection, and preservation of physical evidence

Physical Science Unit

Applies techniques of physics, chemistry, and geology to identify and compare different crime-scene evidence.

Biology Unit

DNA profiling is done on dried bloodstains, body fluids, hairs, fibers, wood, plants, to examine and identify materials.

Firearms Unit

This unit examines firearms, bullets, cartridge cases, shotgun shells, and ammunition.

Document Examination Unit

Studies handwriting and typewriting from suspicious documents to make sure it is authentic.

Photography Unit

Examines physical evidence by using photographic techniques like digital imaging, infrared, ultraviolet, and X-ray photography. Prepares photographic exhibitions to present in the courtroom.

Toxicology Unit

Examines body fluids/organs to see if poisons and drugs are detected.

Latent Fingerprint Unit

Examines evidence to see if invisible fingerprints are present.

Polygraph Unit

Lie detectors, better known as polygraphs, are typical tools of a criminal investigation, not a forensic scientist. It is used to interrogate and investigate crimes.

Voiceprint Analysis Unit

Used to link voices to a particular suspect if there were tape-recorded messages or threats left on the phone. This technique can be considered valid if the sound patterns of an individual are unique to them.

Evidence Collection Unit

When a team of law enforcement starts collecting evidence from a crime scene.

Forensic pathology

Autopsy.

Rigor mortis

When the muscles stiffen after death. Usually sets in about 3-4 hours; then relaxes after about 72 hrs; not cadaveric spasm!

Livor Mortis

Starts 20 mins -3 hrs after death, when blood settles due to gravity (stays there like that).

Algor Mortis

When the body cools to room temperature (depends where they are), about 1-1.5 F per hr.

Forensic Anthropology

Bones (facial reconstruction or age of person, how they were killed with their bones).

Forensic Entomology

Study of bugs (when maggots start to form inside helps with time of death).

Forensic Psychiatry

Criminal profiling (study the mind of serial killers).

Forensic Odontology

Study of teeth (bite marks, identification).

Cybertechnology

The use of technology and specialized techniques to identify, collect, preserve, and analyze digital evidence from electronic devices for legal or investigative purposes.

Cadaveric Spasm

Aka instantaneous rigor. A rare form of muscle stiffening mistaken for rigor mortis but is associated with violent deaths such as drowning.

Infraction

Least punishment and usually a fine (parking ticket).

Misdemeanor

Lesser criminal act - usually monetary fine or short jail time (trespassing, vandalism).

Felony

Very serious crime - usually jail sentence (robbery, murder, rape).

Frye v United States

James Frye convicted of 2nd degree murder. He confessed, but later retracted it- many thought he was innocent, but could not prove it. He was given a lie detector test, but as it was about to be presented in court- a judge did not allow it. He was sentenced to prison. Defendants appealed- but decision was upheld since little was known about science behind the lie detector.

Prongs 1, 2, & 3 of Frye

Has the underlying scientific theory gained general acceptance in the scientific community? Has the scientific technique gained general acceptance in the pertinent scientific community? 'Were proper test procedures employed in this case?'

Expert Testimony

When a qualified forensic scientist provides expert opinions to a court to help a jury understand complex scientific evidence.

Daubert v. Merrell Dow Pharmaceuticals (1993)

Daubert was a minor that was born with birth defects. Mother had been prescribed Benedectin (anti-nausea Medication). Lawsuit against manufacturer.

Daubert Standard

Court decides on the admissibility of expert testimony in the courtroom. 'General Acceptance' is not an absolute prerequisite for admissibility.

Daubert Criteria

1. Technique or theory can be (and has been) tested. 2. Technique or theory has been subject to peer review and publication. 3. Technique's potential rate of error. 4. Existence and maintenance of standards controlling the technique's operation. 5. Method or theory has attracted widespread acceptance within a relevant scientific community.

Means

A person had the ability to do the crime.

Motive

Person had a reason to do the crime.

Opportunity

Person can be placed at the crime.

Serology

the examination and analysis of body fluids like saliva, semen, urine, and blood

plasma

the fluid portion of the blood (55%)

Erythrocytes

red blood cells. They are responsible for oxygen distribution. *No nucleus present

Leukocytes

the white blood cells;

they are responsible for “cleaning”

the system of foreign invaders.

*Nucleus is present

Thrombocytes

platelets are

responsible for blood clotting

Serum

the liquid that separates from

the blood when a clot is formed.

Karl Landsteiner

discovered that there

are four different types of human blood based on the

presence or absence of specific antigens found on

the surface of the red blood cells.

Landsteiner and Weiner

reported the

discovery of the Rh factor by studying the blood of

the Rhesus monkey.

Total body weight

8 percent

liters of blood for males

5-6

liters of blood for females

4-5

A ____ blood volume loss is enough to cause

shock &/or death

40%

ABO blood groups

based on having an A, B, both or no

antigens on red blood cells

Rh factor

may be present on red blood cells; positive if

present and negative if not

Antigen

a substance that can stimulate the body to make

antibodies. Certain antigens (proteins) found in the plasma of

the red blood cell’s membrane account for blood type.

Antibody

a substance that reacts with an antigen

Agglutination

clumping of red blood cells; will result if blood

types with different antigens are mixed

Blood type A has antigen A on the surface of the cell and will

agglutinate

with blood type B.

Blood type B has antigen B on the surface of the cell and will

agglutinate

with blood type A

Blood type AB has antigens A and B on the surface of the

cells

will not agglutinate with either type A or B blood

(because no antibodies).

Blood type O has neither antigen A nor B

will not

agglutinate.

unknown stain at a scene

is it blood? is it human blood?whose is it? determine blood type, alcohol content, drugs present. determine the methods in which the blood may have been deposited

presumptive tests criteria

1) It is sensitive and specific to heme.

 2) It is reliable, stable, economically feasible to use,

and relatively non-toxic.

 3) It is able to meet the Frye standard of general

acceptance to the relevant scientific community.

 4) It is non-destructive to evidence (A presumptive test

shouldn't be the last test you can perform.)

 5) It is non-destructive to the crime scene.

Kastle-Meyer color test

a mixture of

phenolphthalein and hydrogen peroxide; the

hemoglobin will cause the formation of a deep pink

color if blood is present since blood contains

peroxidases.

Kastle-Meyer color test is

not definite and substances other than blood may produce a color change like potatoes and horseradish

Luminol test

reaction with blood to produce light;

extremely sensitive & doesn’t interfere with DNA testing

Benzidine

has been phased out, because it is a

known carcinogen- turned blue

Hemastix or Hamates

tablet

has been found to

be very useful by field

investigators—a dipstick

moistened with distilled

water is placed in contact

with the suspect blood—

reacts with the heme

group causing a green

color change that

indicates a positive result

red blood cells are

most numerous

Precipitin test

human blood is injected into a rabbit;

antibodies are formed; the rabbit’s blood is extracted as an

antiserum; the antiserum is placed on crime scene sample

blood. The sample will react (& precipitate) with human

proteins only if human blood is present.

precipitin test is very

sensitive and requires only a small amount of

blood.

wbcs contain

dna

A blood droplet will remain spherical in space

until

it collides with a surface- (the surface is

called a target) to form a bloodstain.

A droplet falling from the same height, hitting

the same surface at the same angle, will

produce a stain with the same basic shape.

In general, the smaller the spatter, the

greater the energy required to produce them

Conditions Affecting

Shape of Blood Droplet

Size of the droplet

 Angle of impact

 Velocity at which the blood droplet left its

origin

 Height

 Texture of the target surface

On clean glass or plastic

droplet will have

smooth outside edges

On a rough surface

will produce scalloping on

the edges

Questions Answered by

Blood Spatter Interpretation

 The distance between the target surface and the origin

of blood

 The point(s) of origin of the blood

 Movement and direction of a person or an object

 The number of blows, shots, etc. causing the bloodshed

and/or the dispersal of blood.

 Type and direction of impact that produced the

bloodshed

 The position of the victim and/or object during bloodshed

 Movement of the victim and/or object after bloodshed

The more acute the angle of

impact

the more elongated

the stain.

90 degree angles are

perfectly round drops

At about 30 degrees the

stain will begin

to produce a

tail.

The more acute the angle,

the easier it is to determine

the direction of travel.

The location of the blood source

can be determined by

drawing lines

from the various blood droplets to

the point where they intersect.