forensic medicine.pdf

Forensic medicine

Dr.Eyad Abou Asali

Maxillofacial sur.

Ph.d

Definition and scope of Forensic Science

Forensic science is application of science to the law

Forensic science applies the knowledge & technology of science for the definition & enforcement of such laws

Forensic science is the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system

History and development of Forensic

Science

Sir Arthur Conan Doyle popularize crime

detection methods through his fictional character

Sherlock Holmes

Mathieu Orfilia and Alphonse Bertillion

Mathieu Orfila & Alphonse Bertillion

Father of toxicology

Published first scientific treatise on the

detection of poisons & their effects on animals

& this established forensic toxicology as

legitimate scientific endeavor

Father of criminal identification

First scientific system of personal identification

Anthropometry used series of body

measurements to distinguish individuals

Francis Galton, Leon Lattes & Karl Landsteiner

Karl Landsteiner Francis Galton

Francis Galton, Karl Landsteiner

& Leon Lattes

First definitive study of fingerprints & developed a methodology for classifying for filing

Published book titled Finger Prints & explained system for identification

Lansteiner discovered blood groups; A, B, AB, O

Lattes developed procedure determine blood groups from dried bloodstain

Calvin Goddard, Albert S. Osborn & Walter C.

McCrone

Calvin Goddard, Albert S. Osborn & Walter C.

McCrone

Goddard refined techniques for comparing

bullets fired using comparison microscope

Osborn developed fundamental principles of

document examination; authored Questioned

document book

McCrone pioneered use of microscope

Hans Gross, Edmund Locard

Hans Gross Edmund Locard

Hans Gross

Gross; First treatise describing application of

scientific disciplines and scientific method to

field of criminal investigation; produced a classic

book called Criminal Investigation- translated in

English

Edmund Locard

He believed that when a criminal came in

contact with an object, a cross-transfer of

evidence occurred; Hence called Locards

exchange principle

He used a couple rooms and two assistants in an

attic to start the first police lab in Lyon France

USA 1932 first national crime lab developed in USA

with the FBI by J. Edgar Hoover for all law

enforcement agencies

Worlds largest forensic laboratory & performs

over a million examinations every year

1981 FBIs Forensic Science Research &

Training Center 1st time facility conduct

research to develop new & reliable scientific

methods applied to forensic science

Factors determining lab numbers increasing

The demand for labs to perform drug analyses

single most important factor in expansion of

forensic services

Also the advent of DNA profiling has caused the

increase in labs & is the dominant factor in

explaining how general public perceives the

crime lab

Services of the Crime Laboratory

Reasons for variations in services:

Variations in local laws

Different capabilities & functions of organization to

which a laboratory is attached

Budgetary and staffing limitations

Often the sole purpose for crime lab creation has

been to process drug specimens

Basic services provided by full- service

crime labs

Physical science unit: applies principles and

techniques of chemistry, physics & geology to

evidence evaluation; examinations of soil, drugs,

glass, paint, explosives etc are examined

Biology unit: applies principles and techniques to

identify DNA for profiling, stains & body fluids,

hair & fiber comparison, wood and plants

Basic crime lab

Firearms unit: examination of firearms,

discharged bullets, cartridge cases, shot gun

shells, ammunitions, garments and other objects

examined to detect discharge of residues etc.

Document examination unit: handwriting and

typewriting on questioned documents studied;

analysis of paper & ink; erasures, obliterations,

document charred or burned

Basic crime lab

Photography: examine and record evidence;

digital imaging, infrared, ultraviolet, and X-ray

photography techniques make invisible

information visible; court room presentations

Optional services provided by full-

service crime labs

Toxicology unit: body fluids & organs examined

determine presence or absence of drugs &

poisons often this is shared with the medical

examiners or coroners office

Latent fingerprint unit: examination of latent

fingerprints submitted with other lab

examinations


service crime labs

Polygraph unit: polygraph or lie detector used

primarily as a tool of the criminal investigator

Voiceprint analysis unit: cases involving

telephone threats, tape-recorded messages may

use unit to identify persons

Sound patterns are suppose to be unique to the

person & and are captured on a voiceprint


service crime labs

Evidence-collector unit: special trained personnel

collect & preserve physical evidence collected at

the crime scene

Functions of the Forensic Scientists

Analysis of physical evidence: persons skilled in

applying principles & techniques of physical &

natural sciences to analysis of evidence but also

aware of the demands & constraints of court

system

Frye vs. United States: what ever conclusions

were deduced when examining evidence that

method has sufficient established acceptance in

particular field in which it belongs

Analysis of physical evidence

Books and papers as well as a list of experts who

have used a method presented to a court is used

to fit the criteria of generally accepted by the

scientific community

Alternative to Frye standard is Federal rules of

evidence: part of it deals with expert testimony,

admissibility of all evidence

Analysis of physical evidence

continued

1993 the case of Daubert vs. Merrell Dow

Pharmaceutical, Inc. the U.S. Supreme Court

ruled that Frye standard or general acceptance

isnt the prerequisite to admissibility of scientific

evidence; some state courts may apply this ruling

and use the Federal rules of evidence; trial judges

are the gate keepers to determine the

admissibility of scientific evidence; good case for

this ruling: Coppolino vs. State

Provision of Expert Testimony

Person convinces a trial judge he/she has

possesses a skill or knowledge in a trade or

profession aid court in determining truth of

matters at issue considered expert witness;

knowledge obtained by experience, training,

education or combination qualification expert

witness; opposing attorney allowed cross

examine witness to maybe poke holes testimony

Expert witness examples

Training Proper Recognition,

collection & preserving evidence

Specially training personnel to recognize, collect

and preserve physical evidence is highly valued

since without them, evidence could be useless

Police officers or detectives are often trained by

forensic scientists to know what to look for

Other forensic science services

Forensic pathology: involves investigation of

sudden, unnatural, unexplained, or violet deaths;

medical examiners or coroners & answer

questions like who is the victim, what injuries are

present, when did the injuries occur, why and

how were the injuries produced. Primary roll is

to determine cause of death & by autopsy

Forensic pathology

A medical examiner maybe able to determine

time of death by evaluating stage of death of

victim; immediately after death rigor mortis sets

in, appears 1st 24 hrs & disappears after 36 hrs;

livor mortis also sets in and blue to black color

appears on body closed to ground; can be used

to determine if body moved after death; algor

mortis sets in as body loses heat to the ambient

room temperature

Forensic pathology

Time of death also determined by examining

potassium levels in ocular fluid

The rate at which potassium is released into the

vitreous humor maybe used

Also examining stomach can help note what the

victims last meal was

Forensic Anthropology

Concerned with the identification and

examination of human skeletal remains

Examination of skeletal remains reveal their

origin, sex, approximate age, race, skeletal injury

Used to identify victims of mass disasters

Forensic Entomology

Study of insects and their relationship to criminal

investigation

Used to estimate the time of death when it

circumstances surrounding crime unknown

Blow flies first arrive when body starts to

decompose; eggs are laid, and maggots or fly

larvae

Larvae consume tissue & organs

Forensic Entomology

Identification of specific insects present in body

and approximate how long body left exposed by

examining the stage development of fly larvae;

weather conditions and geography affects results

Forensic entomology continued

Forensic psychiatry

Relationship between human behavior and legal

proceedings examined;

Civil cases determine people competent to

make decisions about wills, settling property or

refusing medical treatment

Criminal cases- evaluate behavioral disorders and

determine if people are competent to stand trial;

also behavioral patterns of criminals determine

profile

Forensic Odontology

Identification of victims body is left

unrecognizable state

Teeth enamel, hardest substance in body

Use dental records such as x-rays, dental casts or

photograph of persons mouth comparison made

between dental remains & suspect victim

Use bite marks in some cases like assault

Forensic engineering

Failure analysis, accident reconstruction and

causes and origins of fires or explosions; auto,

plane and others involved

Questions asked

How did an accident or structural failure occur?

Were the parties involved responsible

If so, how were they responsible

Lecture: Forensic Evidence

Physical Evidence

Any material either in gross or trace

quantities that can establish through

scientific examination and analysis

that a crime has been committed.

Forensic laboratories

identification

Items of physical evidence

evaluation individualization

Classification of Physical Evidence

Trace evidence

Direct evidence

Prima facie evidence

Circumstantial evidence

Exculpatory evidence

extremely small items

stands on its own to prove an alleged fact

evidence established by law

incriminates a person

helps to prove that an accused individual is not guilty

Physical evidence utilization in other areas

of forensic investigation

Provides investigative leads for a case

Ties one crime to a similar crime or connects one

suspect with another

Corroborates statements from witnesses to or

victims of a crime

The elements of a crime help to determine what

will be useful as evidence.

Besides knowing what types of evidence to search

for, it is necessary to know where evidence is most

likely to be found.

Characteristics of evidence

E x a m in a t io n a n d a n a ly s is o f p h y s ic a le v id e n c e

p h y s ic a l

id e n t i f ic a t io n

H ig h e s t d e g re e o f s c ie n t i f ic c e r ta in t y p o s s ib le w i thc u r r e n t t e c h n o lo g y

c h e m ic a l

id e n t i f ic a t io n

b io lo g ic a lid e n t i f ic a t io n

Class characteristics

Individual characteristics

features that place the item

into a specific category features that distinguish one item from another of the same type

diffuse reflectance

spectroscopy

Fibers Composition FT-IR

microscopy

Physical properties Solubility,

melting point

Glass Refractive index

Microscopy

Magnesium Atomic

absorption

spectrophotometry

Shoes Miscellaneous Solid-

phase extraction; LC

Powder Drugs of abuse FT-

IR

Evidence Techniques Gunshot residue Atomic absorption

spectrophotometry, scanning

electron microscopy

Clothing Visible reflectance, FT-IR

microscopy, FT- Raman

Pen inks UVvis, LC

Plastic fragments FT-IR, UVvis

Tire fragments Thermal analysis, FT-IR

Food (poisoned) Liquid- and solid-phase

extraction, GC/MS

Fingerprints Fluorescent visualization

Metals Atomic absorption

spectrophotometry, titrations

Types of physical evidence

BODY FLUIDS

Conventional serology:

presence of blood in stains

species identification and ABO

grouping

is not adequately informative to

positive identify a person

DNA analysis can associate victim

and/or suspect with each other or

with the crime scene

BLOODSTAIN PATTERNS

additional information

SEM: erythrocytes & lymphocytes


BODY TISSUES

organ samples collected at

autopsy, including blood, urine

and stomach contents

DRUGS & CONTROLLED

SUBSTANCES

plant materials, powders, tablets,

capsules

toxicological analysis volatile compounds (ethanol, methanol,

isopropanol)

heavy metals (arsenic)

nonvolatile organic compounds (drugs of abuse, pharmaceuticals)

miscellaneous (strychnine, cyanide)

trace drug presence, identity, and

quantity

Black tar heroine wrapped in cellophane


DOCUMENTS

examination

typed, handwritten and printed

materials for evidence of forgery

indented writings, obliterated or

altered writings, used carbon paper,

burned or charred paper

paper and ink analysis

handwriting comparison to determine authenticity

Obliterated writing examination


HAIRS

hairs analysis can determine

morphological features

DNA analysis

toxicological examination

FIBERS

human/animal

race

body area

cosmetic treatments

method of removal (crushed, cut, burned, forcibly removed, fallen out naturally)

can associate a hair to a person

positive identification

presence of drugs and poisons

type

color, composition construction


Two matching hairs identified with the

comparison microscope

Flax fibers viewed with

polarized light


FINGERPRINTS

the strongest possible evidence

of a persons identity

FIRE DEBRIS &

EXPLOSIVES RESIDUE

EXAMINATIONS

identification of accelerants and

explosive residues

Fingerprint Matching

Unburned accelerator liquid on a soot covered carpet


FIREARMS & AMMUNITION

individual microscopic marks

identification, source, operability of

firearms.

detection and characterization of

gunpowder residues

muzzle-to-garments distance

estimation

GLASS FRAGMENTS

Cause of breakage

Direction of breakage force

Physical fitting

Glass fragment comparisons

Photomicrograph: test

bullet - questioned bullet

Glass fracture produced

by a high-speed projectile


PAINT & PAINT PRODUCTS

analysis and comparison of paint

transferred from the surface of an

object to another during the

commission of a crime:

Suspect vehicle impacting a victim

vehicle; a pedestrian or a stationary

object

Tool impacting stationary object

Paint databases can help identify

the year, make and/or color of a

motor vehicle from a chip of paint

left at the scene.

Paint Layers on Wood Surface


TOOLMARK

IDENTIFICATION

microscopic side-by-side comparison

attempts to link a particular tool with a particular mark to the exclusion of any other tool

ROPE & CORDAGE

composition, construction, color and

diameter

Spacing between teeth in gripping -major

role in toolmark examinations

manufacturer


SOILS & MINERALS

comparison between two or

more soils to determine if they

share a common origin

color, texture, composition comparison

WOOD

place the suspect at the crime scene

side or end matching, fracture matching and species identification.

Cross-section - Xylem

Layers of soil exposed at a grave site. Each

layer must be sampled


OILS/GREASE &

COSMETIC PRODUCTS

SHOEPRINTS & TIRE

TREAD IMPRESSIONS

have value for forensic

comparisons.

can provide positive

identification of the suspects

shoes or tires from the suspects

vehicle.

possess unique composition for comparison

Shoeprint

collected

using a

gelatin lifter.

Processing physical evidence

discovering, recognizing and examining it;

collecting, recording and identifying it;

packaging, conveying and storing it;

exhibiting it in court;

disposing of it when the case is closed.

The Crime Scene

Physical Evidence

Physical evidence is any object that can establish

that a crime has been committed or can link a

crime and its victim or its perpetrator.

Forensic science begins at the crime scene. The

investigator must recognize physical evidence &

properly preserve it for laboratory examination.

The evidence must be kept in its original condition

as much as possible.

Securing the Crime Scene

Secure & Isolate the Crime Scene

First priority is medical assistance to individuals &

arresting the perpetrator.

Ropes or barricades and guards will prevent

unauthorized access to the area.

Every person who enters the crime scene has the

potential to destroy physical evidence.

The lead investigator evaluates the scene & determines

the boundaries. They do an initial walk through &

develop a strategy.

All items must be documented & photographed.

Recording the Crime Scene

3 methods of crime-

scene recording:

photography,

sketches, & notes

Ideally all 3 should

be used

Photography

The crime scene should be unaltered, unless injured

people are involved, objects must not be moved

until they have been photographed from all

necessary angles.

If things are removed, added, or positions changed the

photographs may not be admissible evidence.

Photograph completely

Area where crime took place & adjacent areas

Various angles

Photography

If crime scene includes a body:

Take photos to show bodys location & position relative to the

whole crime scene

Take close-up photos of injuries & weapons lying near the body

After the body is removed, photograph the surface underneath.

When size is significant, use a ruler or other measuring

scale

Digital cameras allow for enhancement & examination in

fine detail.

Videotaping a scene is also becoming popular.

Sketches

Once photos are taken, sketch the scene.

A rough sketch is a sketch, drawn at the crime scene, that contains an accurate depiction of the dimensions of the scene & shows the location of all objects having a bearing on the case. All measurements are made with a tape measure

Show all items of physical evidence

Assign each item a number or letter and list it in the legend

Show a compass heading designating north

A finished sketch is a precise rendering of the crime scene, usually drawn to scale. Computer-aided drafting (CAD) has become the standard.

Rough-sketch diagram of a crime

scene. Courtesy Sirchie Finger

Print Laboratories, Inc.,

Youngsville, N.C.,

www.sirchie.com.

Finished-sketch

diagram of a crime

scene. Courtesy

Sirchie Finger Print

Laboratories, Inc.,

Youngsville, N.C.,

www.sirchie.com.

Notes

Note taking must be a constant activity throughout

the processing of the crime scene.

The notes may be the only source of information to

refresh memory.

Tape-recording notes at a scene can be

advantageous detailed notes can be taped much

faster than they can be written.

Dealing with Physical Evidence

Once found, physical evidence must be collected & stored in a way that preserves its integrity for forensic comparison & analysis.

The search for physical evidence must be thorough and systematic, even when suspects are immediately seized.

A forensic scientist is not usually needed at the scene unless the evidence is complex or it is a major crime.

Some police agencies have trained field evidence technicians.

Searching the Crime Scene

One person should supervise & coordinate.

Include all probable entry & exit points in search

What to search for will be determined by the

particular circumstances of the crime.

Examples

Homicide

Hit-and-run

In most crimes, a search for latent fingerprints is

required.

Systematic Search

Collect Physical Evidence

Physical evidence can be anything from massive objects to microscopic traces.

It may be necessary to take custody of all clothing worn by the participants in a crime. Handle carefully & wrap separately to avoid loss of trace evidence.

Critical areas of the crime scene should be vacuumed & the sweepings submitted to the lab for analysis.

Mobile crime-scene vehicles carry supplies to protect the crime scene; photo, collect, & package evidence; & develop latent fingerprints.


The integrity of evidence is best maintained when the item is kept in its original condition as found at the crime scene.

The entire object should be sent to the lab.

If evidence is found adhering to a large structure, remove specimen with forceps or other appropriate tool. In the case of a bloodstain, one may either scrape the

stain off the surface, transfer the stain to a moistened swab, or cut out the area of the object containing the stain.


Each different item or similar items collected at

different locations must be placed in separate

containers.

Packaging evidence separately prevents damage

through contact and prevents cross-contamination.

Autopsy Room Medical examiner or coroner carefully examines the victim

to establish a cause & manner of death.

Tissues are retained for pathological & toxicological

examination.

The following are collected & sent to the lab:

Victims clothing

Fingernail scraping

Head & pubic hairs

Blood (DNA typing)

Vaginal, anal, & oral swabs (in sex-related crimes)

Recovered bullets from the body

Hand swabs from shooting victims (for GSR analysis)

Tools for Evidence Collection

Forceps

Unbreakable plastic pill bottles w/ pressure lids

Manila envelopes, glass vials, pill boxes

Paper bags are better than plasticwhy?

Fire evidence must be kept in an airtight container to

prevent evaporation of petroleum residues

Clothing must be air-dried & placed in individual paper

bags.

http://www.crime-

scene.com/ecpi/evidence_collection.shtml

Chain of Custody

Chain of custody is a list of all people who came into possession of an item of evidence.

Chain must be established whenever evidence is presented in court as an exhibit. Failure to do so may lead to ? Regarding authenticity & integrity of

evidence.

All items should be carefully packaged and marked upon their retrieval at crime sites.

Normally, the collectors initials & date of collection are inscribed directly on the article.

The evidence container must also be marked with collectors initials, location of evidence, & date of collection.

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forensic medicine.pdf