Chapter 1-Introduction

What is forensic science?

The application of science to law

More specifically…

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

Areas of science to be studied





History and development of forensic science

Sir Arthur Conan Doyle (creator of the character, Sherlock Holmes)

·  Described many scientific methods that had not yet been discovered or implemented

Historical Figures in Forensic Science

Mathieu Orfila (1787-1853)

Forensic toxicology

Alfonse Bertillon (1853-1914)

Anthropometry (identification using measurements) 

          Francis Galton (1822 – 1911)

Fingerprinting as a means of identification and the methods for classifying them


1628: Birth of Italian Marcello Malpighi, first to notice patterns of skin on fingers is distinct

1823: Whorls, ellipses, and triangles identified by Jan Evangelista Purkinjie

1880: Fingerprints used by Henry Fauld to identify criminals

1892: Scientific classification of fingerprints developed by Galton

1896: System of matching fingerprints to identify people developed by Ed Henry

1900: Scotland Yard adopts the Henry system of fingerprinting

1902: First person was convicted on fingerprint evidence

1903: NYC police began fingerprint files of arrested persons

1930: National fingerprint file set up by FBI

1960: First laser design to identify fingerprints was developed

Lattes (1887-1954)

    Developed the technique to determine the blood group of a dried bloodstain

Calvin Goddard (1891-1955)

    Compared bullets found with bullets fired from a suspect’s weapon using the comparison microscope establishing the                comparison microscope as indispensable for modern firearms examination

Hans Gross (1847-1915)

    Developed principles of crime investigation using the fields of microscopy, chemistry, physics, mineralogy, zoology, botany,      anthropometry, and fingerprinting.

Albert S. Osbourne (1858-1946)

    Established the standards by which Questionable Documents are studied today

        Walter C. Machrone (1916-2002)

    Established microscopy is an invaluable tool for forensic scientists

        Edmond Locard (1877-1966)

    Responsible for what is now known Locard’s Exchange Principle

Locard’s Exchange Principle

When a criminal comes in contact with an object or a person a cross-transfer of evidence occurs

The birth of the crime lab

Established by the Federal Bureau of investigation in 1932 under the direction under J. Edgar Hoover

Offered forensic services to all law enforcement agencies in United States

Oldest forensic laboratory

Established by August Vollmer

Los Angeles Police Department

Established in 1923

Types of crime labs





Most are part of a Police Department

Others are under the direction of the prosecutor

Still others are under the direction of the medical examiner or coroner

Labs sizes

One to more than 100 personnel

Services may be diverse or specialized

Factors affecting labs size are:

Funds available

Number of cases needing scientific evidence analysis

Types of cases needing scientific evidence analysis

Federal crime laboratories

Federal Bureau of Investigation (FBI)

The Drug Enforcement Administration (DEA)

Bureau of Alcohol, Tobacco, Firearms, and Explosives

US postal inspection service

Comprehensive statewide systems

Regional and satellite laboratories that offer services to most areas of the state, minimizing duplication of services and maximizing interpretation of the evidence 

Local laboratories

Usually operate independently of state crime laboratories and are funded by local government

Services of the Crime Laboratory

Basic Services Provided by Full-Services Crime Laboratories  

Physical science unit handles evidence related to chemistry, physics, and geology

Drugs, glass, pain, explosives, soil and minerals

Biology unit

Staffed by biologists and biochemists 

Handle the identification and DNA profiling of dried bloodstains and other body fluids, the comparison of hairs and fibers in the comparison and identification of botanical specimens

Firearms unit

Examine firearms, discharged bullets, cartridge cases, shotgun shells, and ammunition of all types 

Examine garments and other objects for firearm discharge residues  

Document Examination Unit

Examine handwriting and type writing of questioned documents

Analyze paper and ink, indented writing, erasures, obliterations and burned or charred documents

Photography Unit

Examine and record physical evidence 

Digital imaging, infrared, ultraviolet and X-ray photography to make invisible information visible

Prepare photographic exhibits for courtroom presentation

Optional Services Provided by Full-Service Crime Laboratories

Toxicology unit – Body fluids and organs examined to determine the presence or absence of drugs and poisons

Latent Fingerprint Unit – Responsible for processing and examining evidence for latent fingerprints

Polygraph Unit

Used more by criminal investigators than by the forensic scientist

Voiceprint Analysis Unit

Analyze telephone and recorded messages to tie them to  possible events and suspects

Chapter 2 - The crime scene

Learning objectives-

Processing the crime scene

Recognizing physical evidence

First officer at the crime scene

Why restrict entrance into a crime scene?

Lead investigator’s responsibilities

Recording the scene

Types of documentation

Why take notes and make sketches?

Why document the scene using photographs, sketches AND notes?

Photographing at the crime scene:

Areas to be photographed

Photographing physical evidence


Finished Sketch


Notes should include:

Tape-recording notes

Systematic Search for Evidence

What to search for?

Vehicle searches

Types of Physical Evidence

Microscopic trace cont.

All clothing of suspect collected

Bag separately

Examined for blood

Examined for hairs and fibers

Rooms are vacuumed separately and analyzed for trace evidence

Fingernail scrapings

skin cells (DNA)



Evidence collected from the victim

Provided by medical examiner/coroner

Victims clothing

Fingernail scrapings

Head and pubic hairs

Blood (for DNA typing)

Vaginal, anal and oral swabs

Recovered bullets from the body

Hand swabs from shooting victims

Collecting and packaging physical evidence

Must be handled to avoid change between crime scene and laboratory




Accidental scratching or bending

Handling trace evidence

Leave trace evidence on substrate where it is found

Blood, hairs, fibers and soil particles should not be removed

Remove trace evidence from large or immovable objects

doors, walls, door frames, floors

blood and semen from bed spreads can be removed by cutting around the stain

Tools and packaging carried by evidence collectors


Unbreakable plastic pill bottles

Manila envelopes, screw can glass bottles, and cardboard pill boxes

Resealable plastic bags


Small particles can escape from these envelopes

Special Considerations

Bloodstained clothing should be air dried and stored in a paper bag

Wet articles should not be stored wet

Burned articles should be stored in airtight containers to prevent evaporation of possible accelerants

Maintain the chain of custody

Record of the location of evidence

Marking it for identification

Properly completing evidence submission forms for laboratory analysis

Where the evidence was, and who had it, from the scene of the crime until when it is exhibited in court

Physical evidence must be marked by the following:

Collectors initials and date of collection on the evidence whenever possible

Container holding evidence labeled with:

Collector’s initials

Location of the evidence

Date of collection

Person evidence was delivered to

Eventual destination of evidence

Standard/Reference Samples

Samples of biological evidence from the victim

Samples of biological evidence from the suspect

Samples of biological evidence from anyone else at the crime scene

Physical evidence from suspect/victim that could be linked to the crime


Chapter 3

Physical evidence

Common types of physical evidence

Blood, semen, and saliva






Firearms and ammunition

More physical evidence




Organs and physiological fluids


Petroleum products

Plastic bags

More physical evidence

Plastic, rubber, and other polymers

Powder residues

Serial numbers

Soil and minerals

Tool marks

Vehicle lights

Wood and other vegetative matter

Significance of physical evidence

Must be identified with absolute certainty to determine if a crime has been committed or if the object is related to the crime

Must identify the origin of an object, i.e.are hair samples human, animal or synthetic in origin or are drugs recovered legal or illegal or drugs at all

Process of identification

Adopt standard testing procedure that are accepted for identifying a specific substance

Testing must be specific enough to rule out all other possible substances

Sometimes more than one kind of test must be done to positively identify a substance


Suspect specimen must be compared to a standard/reference specimen

Standard must be put through the same tests

Example: a paint chip from the scene of a hit-and-run accident must be compared to a paint sample from the suspect’s car

If they do not compare the source suspected can be ruled out

Chapter 12



Learning Objectives

After studying this chapter you should be able to:

  1. Know the common ridge characteristics of a fingerprint

  2. List the three major fingerprint patterns and their respective subclasses

  3. Distinguish visible, plastic, and latent fingerprints

  4. Describe the concept of an automated fingerprint identification system ( AFIS)


  5. List the techniques for developing latent fingerprints on porous and nonporous objects

  6. Describe the proper procedures for preserving a developed latent fingerprint


Fundamental Principles of Fingerprints

First Principle: A Fingerprint Is an Individual Characteristic; No Two Fingers Have Yet Been Found to Possess Identical Ridge Characteristics

individuality of a fingerprint is not determined by its general shape or pattern but by a careful study of its ridge characteristics ( also known as minutiae).


Second Principle: A Fingerprint Remains Unchanged During an Individuals Lifetime


Third Principle: Fingerprints Have General Ridge Patterns That Permit Them to Be Systematically Classified


  All fingerprints are divided into three classes on the basis of their general pattern: loops, whorls, and arches.

Classification of Fingerprints

The Henry System

Adopted by Scotland Yard in 1901

Converts ridge patterns on all 10 fingers into letters and numbers in the form of a fraction

Accommodates up to 100,000 sets of prints

Modified to become the FBI System

Primary Classification

 R Index   R Ring  L Thumb L Middle L Little

R Thumb R Middle R Little L Index   L Ring


Based on presence or absence of the whorl pattern


Whorl Present in:

First pair  16 points

Second pair  8  points

Third pair  4  points

Fourth pair  2  points

Fifth pair  1  points


Arches and Loops get 0 points


1 is added to the top and bottom


The Henry number is a class characteristic


Type and position of ridge characteristics give a fingerprint its individuality

Automated Fingerprint Identification Systems (AFISs)

Computerized systems for organizing fingerprint records

Can be operated by cities, counties, local agencies

Integrated Automated Fingerprint Identification Systems


Link state AFIS databases with the FBI database


Operational since 1999

Why all databases aren’t linked

All computer systems in use are not compatible with each other

Differences in software may make it impossible to access


The AFIS uses automatic scanning devices that convert the image of a fingerprint into digital minutiae that contain data showing ridges at their points of termination ( ridge endings) and the branching of ridges into two ridges ( bifurcations).


Fingerprint Powerpoint from web


Chapter 7

The Microscope

Learning Objectives

List and understand the parts of the compound microscope

Define magnification, field of view, working distance, and depth of focus

Contrast the comparison and compound microscopes

Understand the theory and utility of the stereoscopic microscope

Appreciate how a polarizing microscope is designed to characterize polarized light

Appreciate how a microspectrophotometer can be used to examine trace physical evidence

Compare and contrast the image formation mechanism of a light microscope to that of a scanning electron microscope

Outline some forensic applications of the scanning electron microscope

The earliest microscope

the single lens commonly referred to as a magnifying glass

The handheld magnifying glass makes things appear larger than they are

Light rays are refracted, or bent, in passing from the air into the glass and back into the air.

Virtual vs. Real Images

Virtual –

can only be seen by looking through a lens. It cannot be projected

Microscopes Important in Forensic Science

1. The compound microscope

2. The comparison microscope

3. The stereoscopic microscope

4. The polarizing microscope

5. The microspectrophotometer

Compound microscope

Has two lenses

        Ocular or eyepiece


Magnification determined by multiplication of the powers of the two lenses

Image is upside down and backwards


Numerical aperture (NA) found on each objective

The usable magnification of a microscope can be determined by multiplying the NA by 1000

An NA of 0.75 be twice as good as an NA of 1.50

Resolution is the ability to be able to distinguish between two objects

Most oculars have a magnification of 10X

Objectives are commonly 10X, 40X, 100X, 400X

Factors to weigh before choosing a microscope or power to use

Object to be viewed

Large objects need a larger field of view

The higher the power the smaller the field of view

The lower the power the greater the field of view

The higher the power the smaller the depth of field

The lower the power the greater the depth of field

Comparison microscope

Objectives connected with an ocular bridge

Stereoscopic microscope

Used to view things at a lower magnification

Images are seen right side up and not backward

Large field of view

Large depth of field

Large work area

Polarizing microscope

How a polarizing microscope works

Polarizer placed between light source and specimen

Analyzer placed between specimen and eyepiece

If specimen polarizes light it will be detected as a brilliant color


Advantage of using a microspectrophotometer

Small sample size

Can be analyzed using their absorbance spectra

Can distinguish between different inks to detect counterfeit currency, altered documents, connect ink to ransom notes

Analyze paint chips

The scanning electron microscope (SEM)

Image formed by aiming a beam of electrons onto the specimen and studying the electron emissions on a closed-circuit TV.

Electrons emitted from a hot tungsten element (primary electron beam)

Stream of electrons focused by electromagnets onto the surface of the specimen

Electrons emitted from the surface of the specimen (secondary electrons)

20 to 30% of the primary electrons rebound off the surface (backscattered electrons)

Emitted electrons (secondary and backscattered) are collected and amplified signal is displayed on a cathode ray tube (TV tube)

Emitted electrons converted into an image on the cathode ray tube

Major attractions of SEM images

high magnification


great depth of focus

Magnification range

10X to 100,000

Depth of Focus 300 times better than optical systems of similar magnification

How can an SEM be used to individualize or characterize evidence

         Elements emit x-rays of characteristic energy values

         X-ray analyzer can identify elements present in the specimen

         Elements concentration can be determined by measuring the intensity of the x-ray emissions

Application of scanning electron microscopy

         Determine  whether headlights were on or off upon impact of a collision

        Determine whether a suspect has recently fired a gun

             Remove gunshot residue with tape

           Examine tape under SEM

           Beam of electrons will generate x-rays when colliding with primers containing lead, antimony,    and barium.

Elemental Composition of Specimens

can be determined using an x-ray analyzer

x-rays generated when the electron beam strikes a target

x-rays sorted by their energy values to generate a picture

Chapter 8 - Hairs, Fibers, and Paint

Learning Objectives

Recognize and understand the cuticle, cortex, and medulla areas of hair

List the three phases of hair growth

Appreciate the distinction between animal and human hairs

List hair features that are useful for the microscopic comparison of human hairs

Explain the proper collection of forensic hair evidence

Describe and understand the role of DNA typing in hair comparisons

Hair As Physical Evidence

Cannot be individualized based on morphology

Hair is first observed for its structure and color (morphology)

Next, DNA is extracted, isolated and characterized

Morphology of hair

A single hair is an extension of a human epidermal cell that originates from an organ called a Follicle

A hair is composed of a,

Bulb (root)



The hair shaft

Consists of three layers





Made of overlapping scales pointing toward the tip

Scales made by keratinized cells

Scale patterns are species specific

Scale patterns cannot be used to distinguish between two individuals of the same species


Middle portion of the cell

May or may not be present

May be,





Medulla types


Embedded in the follicle

Has three distinct growth phases


May last for six years

Bulb has a flame-like appearance


May last two to three weeks

Root elongates


Two to six months

Root club shaped

Identification and Comparison of Hair

Examine to determine

Animal origin

Nature of crime

Was hair pulled out

Was hair naturally shed

Was hair cut

Age of person losing hair

Needed to identify hair

Compound microscope


Hundreds of prior hair identifications

Features Important in Identification






Medulla pattern

Distribution, shape and color intensity of pigment granules in the cortex

Determination of body location origination of hair


Uniform diameter





Irregular diameter


Triangular in cross-section


Determination of race from hair sample


Diameter round to oval

Pigments evenly distributed


Diameter flat to oval

Pigments unevenly distributed


Medulla continuous

Age and sex determination from hair samples


Iffy at best

Infant hair short and fine


Determinable if skin tag is present

Collection and Preservation of hair samples

Reference samples

50 full-length hairs from scalp

24 full-length hairs from pubic region

Pubic hairs from victim and suspect

Prior to collection of pubic hairs the pubic hair of the suspect and victim should be combed to harvest suspect hairs from victim and victims hair from suspect

Chapter 8 - Forensic Analysis of Glass

Glass particles can be used to place a suspect at the scene of a crime

Chips of broken glass may lodge in clothing of a perpetrator

Glass at the scene of a hit-and-run may confirm the make of the suspect vehicle

Composition of Glass

Glass is a substance composed of sand (silicon oxide) mixed with various metal oxides

Making glass

Mix sand with other metal oxides

Melt at high temperatures

Cool to a rigid condition without crystallization

Soda (sodium carbonate) is added to sand to lower its melting point to make it easier to work with

Lime (calcium oxide) added to prevent "soda-lime" glass from dissolving in water

Soda-lime glass is used to make:

Most window and bottle glass

Molten glass cooled on a layer of molten tin to produce flat glass used in windows (float glass)

Metal oxide used:





Automobile headlights and heat resistant glass contain boron oxide.

        These glasses are known as borosilicates

Tempered glass

Made stronger by rapid heating and cooling of the glass surface

Does not shatter when broken but "dices" or crumbles

Used in the side and rear windows of all cars sold in the United States

Laminated glass

Has one layer of plastic between two layers of window glass

Used for windshields of all cars manufactured in the United States

Comparing Glass Fragments

Greatest evidence value when it can be individualized to one source

Can only be individualized when the crime scene fragments and the suspect fragment can physically fitted together

The edges of the broken glass must match as well as all irregularities and striations on the broken surfaces

Class Characteristics

Class characteristics such as Density and refractive index are used for characterizing glass particles

Density is defined as mass per unit volume

Density = mass


Density is in intensive property

An Intensive Property is not dependent on the size of an object

Solids are more dense than liquids and liquids are more dense than gases

Determining density

Weigh solid on a balance against known standard weights

A solids volume is determined by the volume of water it displaces

Fill a cylinder with a known volume of water (V1)

Add the Object (glass)

Measure New Water Level (V2)

V2 - V1 = volume of the solid

Density comparisons

Glass less dense than a liquid will float on the surface of the liquid

Glass more dense than the liquid will sink

Glass having a similar density of a liquid will be suspended in the liquid


Glass is put in a liquid composed of bromo form and Bromobenzene

Bromoform or Bromobenzene are added until the glass fragment is suspended in the liquid.

Thus, the glass and the liquid have the same density

Did glass come from the same source?

Add suspect glass into solution containing reference source

If both remain suspended then may have come from same source

Get reference glass from four places on sheet of glass to get an average density

Determining refractive index

Immerse glass in a solution which will have its refractive index altered to match the refractive index of the glass

How is this determined?

Becke line disappears

Fragment disappears as contrast between fragment and fluid disappears

Becke line

Halo of light seen at the border of glass fragment and fluid when the glass and fluid have different refractive indices

Changing refractive index of a liquid

Heat the liquid

Use a hot stage on a microscope to observe the becke line disappearance

For each degree change in liquid temperature there is a .0004 decrease in refractive index

Automation of refractive index

GRIM 3 ( Glass Refractive Index Measurement)

Refractive index variation

May vary by as much as .0002 units on a single sheet of glass

Compare your values to FBI database for glass refractive indices

Example of helpfulness of refractive index

a glass fragment with a refractive index value of 1.5290 is found in approximately only 1 out of 2,000 specimens, while glass with a value of 1.5180 occurs approximately in 22 glasses out of 2,000.


Repeated heating and cooling of a glass sample

Changes the refractive index

Tempered glass re-annealing

Refractive index change much greater than in non-tempered glass

Non-tempered glass re-annealing

Glass fractures

Can tell something about the nature of a crime

Can be used to determine projectile type

Can be used to determine direction of projectile

Fracture types



Small, fast moving projectile

Hole smaller diameter on entrance side of glass

Radial and concentric lines

First cracks appear on the side opposite entrance of projectile (radial cracks)

Concentric rings appear on the side the projectile enters first

fracture always terminates at an existing line of fracture.

Collecting glass evidence

All pieces of glass from a source must be collected if there are any hopes of individualizing a glass fragment that was found


Blood Spatter Analysis Chapter 11.ppt

         Gunpowder residues

Modern ammunition is propelled toward the target by expanding gases

Gases are created by the ignition of smokeless powder or dinitrocellulose in a cartridge

         Under ideal conditions

All the powder is consumed during combustion and converted into the rapidly expanding gases

         In reality

Powder is never totally burned

Burned and partially burned particles of gunpowder and smoke are propelled out the gun barrel along with a bullet toward the target

If the muzzle is close to the target particles will be deposited on the target

         Determining distance from target

Why determine distance?

        To determine the details of a crime

        To determine if shooting was self-defense

        To determine if it was a suicide

         When no suspect weapon is recovered

You can state whether a shot could have been fired within some distance from the target

You need the weapon and type of ammunition used to accurately determine distance from target

         Handguns and rifles

Determine distance from gun to victim by examining residue patterns on the victim’s clothes and skin and compare them to test patterns made with the suspect weapon firing at varying distances from the target

Target must be made of similar material to the victims clothing because target material influences residue pattern

Residue pattern varies widely among weapons and ammunition so distance determinations can only be definite if you have the same weapon and same ammunition or, ammunition of the same type and make

         Analyzable characteristics around a bullet hole

When gun is against target or within 1 inch

        A heavy concentration of vaporous lead surrounds bullethole

        Loose threads surround hole it victim is clothed

        Scorch marks from the flame discharge of them why

        Synthetic fibers may be melted

        Blowback produces is stellate pattern around  hole

12 to 18 inches or less from victim

        Halo of vaporous lead (smoke) deposited around a bullet hole

25 inches

        Presence of scattered specks of unburned and partially burned powder without soot

>3 feet – no powder residue.  Only evidence that a bullet made the hole is bullet wife around the hole


A mixture of carbon, dirt, lubricant, primer residue and lead wiped off the bullets surface as it passes through the target

         Other factors affecting distance calculations

        barrel length


Type of ammunition

Condition of the weapon when fired

         Shotgun distances

Must be related to test firings performed with the suspect weapon using the same type of ammunition used in the crime

In absence of weapon, muzzle-to-target distance can be estimated measuring the spread of the discharged shot

         Close range shots

Distance of 5 feet or less

        Shot charge enters a target in a concentrated mass producing a hole slightly larger than the bore of the barrel

Distance of greater than 5 feet (12 gauge)

        Pattern spreads 1 inch for each yard of distance

        10 inch pattern for a distance of 10 yards

        Other factors

Barrel length

Size and quantity of pellets fired

Quantity of powder charge

Choke of the gun

         Choke of the gun

Constriction at the muzzle end of the barrel

The greater the choke the narrower the shotgun pattern the narrower the shotgun pattern and the faster and further the pellets will travel

         Powder residue on Garments

Garments examined microscopically first for the presence of gunpowder residue

Residue may be identified by colors, sizes, and shapes

Invisible residue may be detected using the Greiss test

         Greiss test

Gelatin coated Photographic paper is pressed to the target with a hot iron

Nitrite particles on the target are transferred to the paper

Nitrite particles visualized by chemical treatment

Chemical tests done to detect the presence of lead residue around the bullet hole

         Treatment to detect lead

Target surface sprayed with a solution of rhodizonate

Target sprayed with acid solution

Lead particles turn pink, followed by blue violet

         Primer Residues on the Hands

Detecting primer residues

Dermal nitrate test

        Hot paraffin or wax painted onto suspect’s hands with a paintbrush

        Wax allowed to dry

        Wax removed and tested with diphenylamine

        Blue color indicates a positive reaction

         Problems with dermal nitrate test

False positives result from reactions with fertilizers, cosmetics, urine and tobacco


DNA In Forensics

Forensic DNA Testing