CH 1 Forensic Scientists n Other Services.ppt

7/27/2019 CH 1 Forensic Scientists n Other Services.ppt

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ORGANIZATION

of a

CRIME LABORATORY


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Attributed to an increase in crime rates,primarily drug related crimes.

Drug seizures must be sent to a lab forconfirmation by chemical analysis before a

judge can rule on a case.

Currently over 300 public crime labsoperating under federal, state, countyand municipal governments.

Rapid Increase in Crime Labs


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4 major FEDERAL crime labs:1. FBI - Federal Bureau of Investigation Largest crime lab in the world

Capable of investigating a broad range of crimes

2. DEA - Drug Enforcement Administration Primary focus: analysis, production, sale, &

transportation of illegal drugs

3. ATF - Alcohol, Tobacco, Firearms & Explosives Primary focus: analysis of alcoholic beverages, tax

law documents, weapons, explosive devices Gun Control Act of 1968

Organized Crime Control Act of 1970

4. USPS - U.S. Postal Service


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SERVICES OF A CRIME LAB

Crime labs vary in the services theyprovide due to Differences in local laws

The labs capabilities Budget limitations

Many crime labs were simply created forprocessing drugs.

Only a few labs offer a multitude ofservices.


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Full Service Crime Labs

Labs that have the following units.

Physical Science: Drugs, glass, paint, explosives, soil, & trace

physical evidence.

Biology: DNA, bloodstains, semen, saliva, hair & fiber

comparisons, botanical materials (wood/plants).

Firearms: Examines of firearms, discharged bullets, cartridge

cases, shotgun shells, ammunition of all types, clothing (for

gun residue), tool-mark comparisons.

Document Examination : examines handwritten &

typed/printed documents for authenticity (forgery), ink & paperanalysis.

Photography: Uses digital imaging, infrared, ultraviolet, & x-ray

photography AND courtroom photos.


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Other Optional Serviceso Toxicology: Body fluids & organs tested for

drugs/poisons.oIntoxilyzer an instrument that detects the

level of alcohol consumed by someone.

o Latent Fingerprint Unit

o Polygraph: lie detection

o Voiceprint Analysis: telephone threats & recordedmessages

osound spectrograph an instrument thattransforms speech into a visual graphic displaycalled a voiceprint.

o Evidence-Collection Unit: they only collect; they do

NOT analyze.


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Functionsof a

Forensic Scientist


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Functions of a Forensic Scientist

Applies Science to Law

Analyzes Physical Evidence

Gives Expert Testimony Trains Law Enforcement

Available 24-7


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Analysis of Evidence

They have to

RECOGNIZE

IDENTIFY

COLLECT

PRESERVE

EVALUATE

INDIVIDUALIZE physical evidence


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DATA is basis of all conclusions

ACCURATE DATA is derived from careful

collection of evidence

POOR EVIDENCE COLLECTION or

HANDLING can result in wrong

conclusions (i.e. OJ Simpson case)

GI-GO: Garbage in garbage out

DOCUMENTATION is ESSENTIAL


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Use of SCIENTIFIC METHODS

What is EVIDENCE vs. COINCIDENCE?

Give WEIGHT (ranking) to resultsAttach a DEGREE of CERTAINTY

Apply results to theories in order to

PROVE or DISPROVEComponents must ADD UP to THEORY


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Its ALL about the EVIDENCE!

The training & competence of forensic

scientists & the sophistication of their

equipment have little or no value if relevantevidence cannot be recognized, collected, &

preserved!


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Physical Evidence


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Common Examples of Physical

Evidence

Blood, Semen, Saliva

Hair

Samples from body

organs Fingerprints

Documents

Serial numbers

Impressions

glass

Soil & minerals

Fibers

Petroleum residues

Paint, plastic & rubber

Powder residue

Firearms & explosives

Wood & vegetativefragments


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The Marsh Test In 1832 police arrested John

Bodle for lacing hisgrandfather's coffee withpoison.

Chemist James Marsh tested

the drink in his laboratory, &confirmed the presence ofarsenic by producing a yellowprecipitate of arsenic sulfide.

But the precipitate wasunstable &, by the time oftrial, had deteriorated.Without forensic proof, Bodle

was acquitted.


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Physical Evidence

Forensic Scientists must be aware of the

demands & constraints imposed by the judicial

system.

Evidence must satisfy the criteria of admissibility

that have been established by the courts.

New scientific techniques to analyze evidence

are constantly developed & challenged by the

courts until proven acceptable by the scientific

community.


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POLICE LINE DO NOT CROSS


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POLICE LINE DO NOT CROSS

POLICELINEDONOTCROSS


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Carmichael v. Kumho Tire Co. The Carmichaels had a fatal accident when their

minivans rear tire blew out. One of the passengersdied & others were severely injured.

They sued the tire manufacturer, claiming the tire

was defective & it caused the accident. Their caserelied largely on testimony from a tire expert.

The judge referred to the Daubert standard& foundthe tire expert's methods not to be scientificallyvalid, and hence excluded his testimony.

They lost but appealed & eventually won!


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Expert Testimony


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Expert Testimony

Forensic Scientists are often called upon

to act as Expert Witnesses.

Expert Witness someone that

possesses a particular skill or knowledge

on a topic that will aid the court in

determining the truth.


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Expert Testimony

The credentials that makes someone anexpert is often ambiguous & highlysubjective.

Expert witnesses must be:

Advocates of Truth

Objective (no personal opinions)

Experienced (# of years in their field) Trained (special courses)

Educated (degrees in their field)


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Expert Testimony

An expert witness is allowed to bechallenged by the opposing attorney.

They cross-examine the expert to find anyweaknesses in background & knowledge.

Even if someone is considered an expert,a judge or jury might not consider theirtestimony that important anyway.


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Other Forensic

Science Services


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Forensic Pathology

Investigation of sudden, unnatural, unexplained

or violent deaths

Autopsy medical dissection to establish the

cause of death (usually performed by ME or coroner)

Death can be classified as:

natural,

homicide, suicide,

accident

or undetermined

Time Since Death (TSD)


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Time Since Death (TSD)

determined by rigor mortis

Muscles relax then shorten & become stiff

1st 24 36 hours after death

livor mortis

Heart stops pumping & blood settles in areas of thebody closest to the ground.

Skin appears dark blue or purple

Up to 12 hrs after death

algor mortis Body loses heat until it reaches room temperature

Influenced by location, victim size, clothing, & weather

General Rule: 1 hr after death, heat is lost at 1-1.5

degrees per hour


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Forensic Medicine

Investigation of illnesses that cannot be

determined.

Takes patients symptoms & uses facts to

analyze & interpret.

Usually a last result. Doctors cannot find

cause of ailment, so this is employed.

HOUSE, M.D.


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Forensic Anthropology

Examine & Identify Skeletal remains

Bones can reveal

species, sex,

approximate age,

race skeletal injury

Facial reconstruction can help identify

John or Jane Doe


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Forensic Entomology

Study of insects to estimate the time of

death

Insects lay eggs that hatch into larvae Stages of development tell how long ago

the eggs were laid

Temperature & other weather conditionsaffect the development


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Forensic Psychiatry

Study of human behavior

Determine if persons are competent to

stand trial Develop a suspects behavioral profile

based on previous patterns of other

criminals


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Forensic Odontology

Study of teeth characteristics, alignment

and the overall structure of the mouth to

identify a person

Bite mark analysis compares marks on a

victim to the teeth of the suspect


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Forensic Engineering

Investigation of

structural failures,

accident reconstruction causes of fires

Attempts to determine if human

intervention caused the structural failure Utilizes computer models & architectural

models to help courts visualize crimescenes


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