Sarfaraz HussainSarfaraz HussainRoll#2054Roll#2054

Gcu FaisalabadGcu FaisalabadTOPIC: Forensic DNA AnalysisTOPIC: Forensic DNA Analysis

Forensic DNA AnalysisForensic DNA Analysis

DNA is the Genetic MaterialDNA is the Genetic Material

Sources of Biological Evidence

Blood

Semen

Saliva

TeethBone

Hair

Tissue

Feces

Urine

Skin CellsSweat

Critical to Locate EvidenceCritical to Locate Evidence It is important to have good crime scene It is important to have good crime scene

analysis.analysis. Evidence technicians, trained in DNA work, Evidence technicians, trained in DNA work,

extract material from evidence. (BS in extract material from evidence. (BS in Science)Science)

Crime Scene analysts identify evidence at Crime Scene analysts identify evidence at the crime itself. (BS in Criminal Justice)the crime itself. (BS in Criminal Justice)

Forensic DNA analysts extract the DNA Forensic DNA analysts extract the DNA and perform the reactions and analyze the and perform the reactions and analyze the results. (MS in science)results. (MS in science)

What is Blood?What is Blood? Slightly alkaline fluid made up of Slightly alkaline fluid made up of

water, cells, enzymes, proteins, water, cells, enzymes, proteins, glucose, hormones, organic and glucose, hormones, organic and inorganic substancesinorganic substances

Circulates throughout the bodyCirculates throughout the body• Supplied nutrients and oxygen to the Supplied nutrients and oxygen to the

bodybody• Removes wasteRemoves waste

Blood CellsBlood Cells Cells mature and differentiate into Cells mature and differentiate into

several classes of cellsseveral classes of cells• Red blood cellsRed blood cells• White blood cellsWhite blood cells• PlateletsPlatelets

Red Blood CellsRed Blood Cells Also known as ErythrocytesAlso known as Erythrocytes Have no nucleusHave no nucleus

• Therefore note useful for DNA analysisTherefore note useful for DNA analysis 6-8 um in size6-8 um in size ~45% total volume of blood~45% total volume of blood Most abundant cell in the bloodMost abundant cell in the blood

Red Blood CellsRed Blood Cells

White Blood Cells (WBC)White Blood Cells (WBC)

Also known as leukocytesAlso known as leukocytes Produced in bone marrowProduced in bone marrow WBCs have a nucleusWBCs have a nucleus

• Useful for DNA analysisUseful for DNA analysis Vital source of defense against external Vital source of defense against external

organismsorganisms White blood cells also clean up dead White blood cells also clean up dead

cells and tissue debris that would cells and tissue debris that would otherwise accumulate and lead to otherwise accumulate and lead to problems.problems.

Red and White Blood CellsRed and White Blood Cells

RBCs

WBCs

PlateletsPlatelets

Irregularly-shaped, colorless Irregularly-shaped, colorless bodies produced in the bone bodies produced in the bone marrowmarrow

Their sticky surface lets them, Their sticky surface lets them, along with other substances, form along with other substances, form clots to stop bleeding.clots to stop bleeding.

Only active when damage occurs Only active when damage occurs to the circulatory system walls.to the circulatory system walls.

PlasmaPlasma

Liquid potion of bloodLiquid potion of blood• Composed of water, proteins, Composed of water, proteins,

electrolyteselectrolytes• Blood cells and platelets are Blood cells and platelets are

suspended in plasmasuspended in plasma Regulates osmotic pressureRegulates osmotic pressure The transport medium forThe transport medium for

Glucose, lipids, hormones, clotting Glucose, lipids, hormones, clotting factors, wastefactors, waste

SerumSerum

Clear liquid that is left after blood Clear liquid that is left after blood coagulatescoagulates

Plasma without the clotting factorsPlasma without the clotting factors

Analyzing Genetic Variation in Analyzing Genetic Variation in Blood ForensicallyBlood Forensically

Hemoglobin (RBC)Hemoglobin (RBC) Peroxidase-like activity can cleave HPeroxidase-like activity can cleave H22OO22

Blood Group Antigen (RBC)Blood Group Antigen (RBC) ABO groups (on surface of RBC’s)ABO groups (on surface of RBC’s)

DNA (WBC)DNA (WBC) Found in nucleus of WBCsFound in nucleus of WBCs

Proteins (Plasma)Proteins (Plasma) Serum used in species testingSerum used in species testing

Blood TypingBlood Typing All Blood groups All Blood groups

are determined by are determined by the antigens on the antigens on their red blood their red blood cells.cells.

Antibody-B reacts Antibody-B reacts with A-antigen and with A-antigen and vice versavice versa

Blood Blood Type:Type:

Antigens Antigens on RBCson RBCs

Antibodies Antibodies in serumin serum

AA AA Anti-BAnti-B

BB BB Anti-AAnti-A

ABAB ABAB Neither Neither Anti-A or Anti-A or Anti-BAnti-B

OO Neither Neither A nor BA nor B

Both Anti-Both Anti-A and A and Anti-BAnti-B

Blood TypingBlood Typing

Rh factorRh factor + Rh factor means your blood contains a + Rh factor means your blood contains a

protein also found in Rhesus monkeys (85% protein also found in Rhesus monkeys (85% of people are Rh +)of people are Rh +)

Combined with the ABO system, the Combined with the ABO system, the Rh factor can exclude suspects as Rh factor can exclude suspects as well as include with some rarer well as include with some rarer blood types.blood types.

O+ 1 in 3 persons O- 1 in 15 personsO+ 1 in 3 persons O- 1 in 15 persons AB- 1 in 167 persons B- 1 in 67 personsAB- 1 in 167 persons B- 1 in 67 persons

Presumptive TestsPresumptive Tests

Presumptive Tests are used to tell if a Presumptive Tests are used to tell if a sample is blood. sample is blood.

Other presumptive tests can tell if a Other presumptive tests can tell if a sample is human or primate blood. sample is human or primate blood.

This is important to avoid wasting time This is important to avoid wasting time trying to purify DNA from red paint and trying to purify DNA from red paint and meat juices. meat juices.

Take a small rubbing from the stain, Take a small rubbing from the stain, react it with chemicals and look for a react it with chemicals and look for a color change. color change.

Phenolphthalein TestPhenolphthalein Test

Phenolphthalein TestPhenolphthalein Test

LimitationsLimitations• Sensitivity ~1/100,000 dilution Sensitivity ~1/100,000 dilution • Lack of SpecificityLack of Specificity

Chemical oxidants (bleach), vegetable Chemical oxidants (bleach), vegetable peroxidases cause reactionsperoxidases cause reactions

Will not detect differences in animal or Will not detect differences in animal or human bloodhuman blood

• StabilityStability Relatively stable if the reagents are Relatively stable if the reagents are

stored separately and refrigeratedstored separately and refrigerated

Leucomalachite GreenLeucomalachite Green

Leucomalachite GreenLeucomalachite Green

Sensitivity ~1/1000 dilutionSensitivity ~1/1000 dilution Lack of specificityLack of specificity

• Chemical oxidants and vegetable Chemical oxidants and vegetable peroxidases cause a reactionperoxidases cause a reaction

• Will not detect differences in animal Will not detect differences in animal or human bloodor human blood

Stability- similar to Stability- similar to PhenolphthaleinPhenolphthalein

HemastixHemastix

Reagent strips with TMB ends Reagent strips with TMB ends (Tetramethylbenzadine)(Tetramethylbenzadine)

TMB changes from orange to green TMB changes from orange to green when it comes into contact with bloodwhen it comes into contact with blood

Used for occult blood in stoolUsed for occult blood in stool Somewhat quantitative Somewhat quantitative Very sensitiveVery sensitive TMB dangerousTMB dangerous

LuminolLuminol

LuminolLuminol

How it worksHow it works• The iron in hemoglobin acts as a The iron in hemoglobin acts as a

catalyst to cause a reaction between catalyst to cause a reaction between the luminol and Hthe luminol and H22OO22

• Luminol loses nitrogen and hydrogen Luminol loses nitrogen and hydrogen and gains oxygenand gains oxygen

• This results in 3-aminopthalate which This results in 3-aminopthalate which is energized and emits lightis energized and emits light

LuminolLuminol

Sensitivity ~10Sensitivity ~10-8-8 (most sensitive (most sensitive presumptive)presumptive)

SpecificitySpecificity• Bleach, metals, chemical oxidants, plant Bleach, metals, chemical oxidants, plant

peroxidases light up too.peroxidases light up too.• Will not differentiate animal and human Will not differentiate animal and human

bloodblood Very unstable ~4 hours for the mixtureVery unstable ~4 hours for the mixture Mostly used at crime scenes Mostly used at crime scenes

• Can dilute out bloodCan dilute out blood

ABAcard HematraceABAcard Hematrace

Confirmatory test (shows that it is Confirmatory test (shows that it is human or primate blood, since the human or primate blood, since the other tests can be nonspecific)other tests can be nonspecific)

Tests for human hemoglobin (Hb)Tests for human hemoglobin (Hb)

ABAcard HematraceABAcard Hematrace

SemenSemen Most common crime with DNA Most common crime with DNA

evidence is sexual assaultevidence is sexual assault Sperm have DNA which can be well Sperm have DNA which can be well

preserved if dried on cloth.preserved if dried on cloth.

Semen CompositionSemen Composition Semen is a fluid of complex Semen is a fluid of complex

composition, produced by the male composition, produced by the male sex organssex organs

There is a cellular component, There is a cellular component, spermatozoa, and a fluid component, spermatozoa, and a fluid component, seminal plasmaseminal plasma

Seminal PlasmaSeminal Plasma

Composed of salts, sugars, lipids, Composed of salts, sugars, lipids, enzymes, nutrients, proteins, hormones, enzymes, nutrients, proteins, hormones, basic amines (spermine), P30, flavinsbasic amines (spermine), P30, flavins

Enzymes- Acid PhosphataseEnzymes- Acid Phosphatase P30 ( a prostate specific protein used in P30 ( a prostate specific protein used in

prostate cancer tests)prostate cancer tests) FlavinsFlavins The components originate from several The components originate from several

sources, including seminal vesicles and sources, including seminal vesicles and the prostate glandthe prostate gland

Sperm CellsSperm Cells Sperm are the male reproductive Sperm are the male reproductive

cellscells Each consists of a head, tail and mid-Each consists of a head, tail and mid-

piecepiece• In humans, the head is a tiny disc, about In humans, the head is a tiny disc, about

4.5 um long and 2.5 um wide4.5 um long and 2.5 um wide• The tail is about 40 um long, and is The tail is about 40 um long, and is

rapidly lost in ejaculaterapidly lost in ejaculate

Is a sperm a sperm?Is a sperm a sperm?

Human sperm vs. animal spermHuman sperm vs. animal sperm Dogs have similarly shaped sperm, Dogs have similarly shaped sperm,

but are about three times larger but are about three times larger than human spermthan human sperm

Other animals have differently Other animals have differently shaped spermshaped sperm

Situations?Situations?

Presumptive tests for SemenPresumptive tests for Semen Semen stains fluorescent under UV lightSemen stains fluorescent under UV light

• It is common practice to visually assess items of It is common practice to visually assess items of evidence under UV light to located possible semen evidence under UV light to located possible semen stainsstains

What fluoresces in semen?What fluoresces in semen?• The intensity of the fluorescence can be affected by the The intensity of the fluorescence can be affected by the

substrate, concentration of the stain, and other body substrate, concentration of the stain, and other body fluidsfluids

Identified on crime scene or in lab by Evidence Identified on crime scene or in lab by Evidence TechnicianTechnician

What else fluoresces?What else fluoresces?• Fibers, coffee, food, detergent, most organic stainsFibers, coffee, food, detergent, most organic stains

Presumptive test: SemenPresumptive test: Semen Acid Phosphatase TestAcid Phosphatase Test

• Human semen contains high concentrations of acid Human semen contains high concentrations of acid phosphatase (AP), which can therefore be the basis of phosphatase (AP), which can therefore be the basis of the screening testthe screening test

• While AP is detected in high concentrations in semen, it While AP is detected in high concentrations in semen, it can also be detected in other body fluidscan also be detected in other body fluids

False positivesFalse positives• Vaginal acid phosphataseVaginal acid phosphatase• Fecal materialFecal material• Plant matterPlant matter• Spermicides (orange)Spermicides (orange)• Some feminine hygiene productsSome feminine hygiene products

Confirmatory Tests: SemenConfirmatory Tests: Semen

• P30 identificationP30 identification Found in semenFound in semen

• MicroscopyMicroscopy Identification of spermIdentification of sperm

Prostate Specific Antigen (P30)Prostate Specific Antigen (P30) Antigen made in the prostate glandAntigen made in the prostate gland Weighs 30kDWeighs 30kD Liquefies semen and is instrumental Liquefies semen and is instrumental

in dissolving the cervical mucous cap in dissolving the cervical mucous cap for sperm entryfor sperm entry

Early detection methods-Early detection methods-electrophoretic double diffusion, electrophoretic double diffusion, Ouchterlony (precipitation band)Ouchterlony (precipitation band)

P30 TestP30 Test

Sperm IDSperm ID Confirm the presence of semen by Confirm the presence of semen by

microscopically identifying sperm microscopically identifying sperm cellscells

Most common staining method is Most common staining method is Kernechtrot picroindigocarmine Kernechtrot picroindigocarmine stain- Alsp called Christmas Tree stain- Alsp called Christmas Tree StainStain

Prepared or commercially suppliedPrepared or commercially supplied

Human

Dog

Collection of Hair SpecimenCollection of Hair Specimen

HairHair Composed of cylindrical structures or Composed of cylindrical structures or

shafts made up of tightly compacted cells shafts made up of tightly compacted cells that grow from folliclesthat grow from follicles

Diameter ranges from 15-120 Diameter ranges from 15-120 µmµm• Depends on type of hair and body regionDepends on type of hair and body region

Root material can be used for nuclear DNA Root material can be used for nuclear DNA testingtesting

Shaft material can be used for some Shaft material can be used for some mitochondrial DNA testing too.mitochondrial DNA testing too.

Hair RootsHair Roots

Pulled Forcibly Removed Shed

Tip of the ShaftTip of the Shaft

Burned Cut Razored Split

HairHair

Basic Evaluation StepsBasic Evaluation Steps1.1. Determine if the sample is a hairDetermine if the sample is a hair2.2. Determine if the hair is of human originDetermine if the hair is of human origin3.3. Determine if the hair has root material-Determine if the hair has root material-

suitable for nuclear DNA analysis suitable for nuclear DNA analysis (Characteristic of a particular growth phase )(Characteristic of a particular growth phase )

4.4. If not suitable for nuclear DNA analysis, If not suitable for nuclear DNA analysis, determine if the hair is sufficient in size for determine if the hair is sufficient in size for mtDNA analysis (2-3cm)mtDNA analysis (2-3cm)

HairHairDNA analysis of hair is a destructive DNA analysis of hair is a destructive technique and results in the technique and results in the consumption of portions of the hairconsumption of portions of the hair

• Hair characteristics, such as color, Hair characteristics, such as color, length, shape, and texture should be length, shape, and texture should be noted in the case file for future noted in the case file for future reference prior to DNA analysisreference prior to DNA analysis

Notes and digital imagesNotes and digital images

Saliva Saliva

Colorless fluid secreted by 3 glands Colorless fluid secreted by 3 glands in the mouthin the mouth• Sublingual, submandibular, and Sublingual, submandibular, and

parotidparotid• Saliva from parotid glands contain Saliva from parotid glands contain

amylases, enzymes, which aid in the amylases, enzymes, which aid in the digestion of carbohydratesdigestion of carbohydrates

• Saliva is composed of electrolytes, Saliva is composed of electrolytes, enzymes, mucusenzymes, mucus

SalivaSaliva

Screening for saliva is based on Screening for saliva is based on detection of high levels of amylase in detection of high levels of amylase in the samplethe sample

• It is not a confirmatory test; amylase is It is not a confirmatory test; amylase is found in other body fluids found in other body fluids

Serum, urine, sweat, lip mucous, semen, Serum, urine, sweat, lip mucous, semen, feces, etc.feces, etc.

• The concentration of amylase in saliva is The concentration of amylase in saliva is variable among individual; if amylase is variable among individual; if amylase is not detected in a sample it does not not detected in a sample it does not mean saliva is not presentmean saliva is not present

SalivaSaliva UV light can be used to aid in UV light can be used to aid in

locating saliva stainslocating saliva stains• The intensity of the fluorescence can be The intensity of the fluorescence can be

affected by the substrate, concentration affected by the substrate, concentration of the stain, and other body fluidsof the stain, and other body fluids

• Saliva does not fluoresce as intensely as Saliva does not fluoresce as intensely as semensemen

AmylaseAmylase One of the earliest tests for amylase was One of the earliest tests for amylase was

the starch-iodine testthe starch-iodine test Iodine solutions cause starch to turn a Iodine solutions cause starch to turn a

deep blue colordeep blue color Amylase is a starch hydrolyzing enzymeAmylase is a starch hydrolyzing enzyme The presence of amylase causes the The presence of amylase causes the

disappearance of the blue color (due to disappearance of the blue color (due to hydrolysis of the starch) and can be used hydrolysis of the starch) and can be used an indicator for the presence of amylasean indicator for the presence of amylase

Phadebas Phadebas ®® Test Test

http://www.uni-wuerzburg.de/ddch/liquits/Amylasedirekt.jpg

Positive testNegative test

Vaginal SecretionsVaginal Secretions

Vaginal secretions are a complex Vaginal secretions are a complex mixture of cells and secretions mixture of cells and secretions

There is no confirmatory test to There is no confirmatory test to identify vaginal secretionsidentify vaginal secretions

Several screening tests based on Several screening tests based on microscopy have been proposed. microscopy have been proposed. 

Vaginal SecretionsVaginal Secretions Vaginal epithelial cells are large, and Vaginal epithelial cells are large, and

many contain glycogen (a polysaccharide) many contain glycogen (a polysaccharide) which can be demonstrated by staining which can be demonstrated by staining with iodine in the form of a solution or with iodine in the form of a solution or exposing to iodine vapor.  exposing to iodine vapor. 

The presence of glycogenated cells is The presence of glycogenated cells is variable depending on the stage of the variable depending on the stage of the woman’s cyclewoman’s cycle

Glycogenated cells can be found in other Glycogenated cells can be found in other body secretions (i.e. oral, anal)body secretions (i.e. oral, anal)

Fecal MaterialFecal Material Feces are food residues passed after Feces are food residues passed after

completion of travel through the completion of travel through the digestive systemdigestive system

Has a characteristic odor mainly due Has a characteristic odor mainly due to skatole, an organic compound that to skatole, an organic compound that occurs naturally in fecesoccurs naturally in feces

Fecal MaterialFecal Material

MicroscopyMicroscopy Microscopy has been used to identify fecal Microscopy has been used to identify fecal

materialmaterial• Looking for undigested residues of food Looking for undigested residues of food

materialmaterial Chemical TestsChemical Tests Detection of urobilinogen, a bile pigment Detection of urobilinogen, a bile pigment

excreted in feces, which may be detected excreted in feces, which may be detected using its fluorescent reaction to Edelman’s using its fluorescent reaction to Edelman’s reagentreagent

UrineUrine No confirmatory tests for the presence of No confirmatory tests for the presence of

urineurine Urine stains fluorescent under ultraviolet lightUrine stains fluorescent under ultraviolet light

• This can be useful for locating stains prior to This can be useful for locating stains prior to chemical testingchemical testing

Has a characteristic odorHas a characteristic odor Contains a large amount of urea, a chemical Contains a large amount of urea, a chemical

byproduct of normal metabolic processes in byproduct of normal metabolic processes in the bodythe body• Identification of high levels of urea can serve as a Identification of high levels of urea can serve as a

screening test for urine in fluids or stainsscreening test for urine in fluids or stains• Perspiration can give reactions similar to urinePerspiration can give reactions similar to urine

UrineUrine Contains creatinine, which is a breakdown Contains creatinine, which is a breakdown

product of creatine (an important part of product of creatine (an important part of muscle)muscle)

Over time, the creatine molecule gradually Over time, the creatine molecule gradually degrades to creatininedegrades to creatinine

Creatinine is a waste product that is Creatinine is a waste product that is excreted from the body entirely by the excreted from the body entirely by the kidneyskidneys• Identification of creatinine can serve as a Identification of creatinine can serve as a

screening test for urine in fluids or stains screening test for urine in fluids or stains

CreatinineCreatinine

Jaffe TestJaffe Test One of the oldest tests for the One of the oldest tests for the

detection of creatinine-1886detection of creatinine-1886 Creatinine forms a red compound Creatinine forms a red compound

with picric acid (Jaffe test)with picric acid (Jaffe test)

Teeth and BoneTeeth and Bone DNA can be extracted from nucleated cells DNA can be extracted from nucleated cells

preserved inside teeth. preserved inside teeth. DNA can be preserved in bone marrow, DNA can be preserved in bone marrow,

especially if bones are dry.especially if bones are dry. Teeth are drilled in the lab and the Teeth are drilled in the lab and the

material is extracted and DNA is material is extracted and DNA is extracted.extracted.

Bone is drilled out and DNA is extracted Bone is drilled out and DNA is extracted Teeth and bones are best tissue for DNA Teeth and bones are best tissue for DNA

analysis from skeletal remains.analysis from skeletal remains.

Touch EvidenceTouch Evidence Epithelial cells that have been transferred from Epithelial cells that have been transferred from

the person to the evidence via “touching”the person to the evidence via “touching” These samples tend to have low amounts of These samples tend to have low amounts of

DNADNA Would expect body fluid stains to have more Would expect body fluid stains to have more

DNA than touch evidenceDNA than touch evidence Body fluid comparison:Body fluid comparison:

• Undiluted semen (with sperm) stain > blood stainUndiluted semen (with sperm) stain > blood stain• Both blood and semen > saliva stainBoth blood and semen > saliva stain• Body fluids > wear area stain (armpits, collar of a Body fluids > wear area stain (armpits, collar of a

shirt)shirt)

Case ProcessingCase Processing

Includes:Includes:Location and Collection of EvidenceLocation and Collection of Evidence Collection Techniques Collection Techniques Preservation of EvidencePreservation of Evidence Packaging and StoragePackaging and Storage Documentation-Chain of CustodyDocumentation-Chain of Custody Casework AnalysisCasework Analysis

Location and Collection of EvidenceLocation and Collection of Evidence

Evidence:Evidence: Physical Evidence - any tangible Physical Evidence - any tangible

object that can connect an offender object that can connect an offender to a crime scene, an offender to a to a crime scene, an offender to a victim, a victim to a crime scene etc. victim, a victim to a crime scene etc.

Biological Evidence is physical Biological Evidence is physical evidenceevidence - but is not always visible - but is not always visible to the naked eyeto the naked eye

Sources of Biological Evidence

• Blood• Semen• Saliva• Urine/Feces• Hair• Teeth/Bone• Tissue• Cells

Reference SamplesReference Samples

BloodBlood• Blood transfusionsBlood transfusions

Buccal Swabs/SalivaBuccal Swabs/Saliva ClothingClothing

• Last resort secondary standardLast resort secondary standard Other Secondary StandardsOther Secondary Standards

• Toothbrush, hairbrush, glasses, etc.Toothbrush, hairbrush, glasses, etc. Other standardsOther standards

• All persons who had access to a crime scene All persons who had access to a crime scene should be documentedshould be documented

• May be necessary to collect samples from May be necessary to collect samples from these individualsthese individuals

Actions to AvoidActions to Avoid Touching any areas/items where DNA Touching any areas/items where DNA

may existmay exist Touching your face, nose, hair, and Touching your face, nose, hair, and

mouth when collecting and mouth when collecting and packaging evidencepackaging evidence

Sneezing, coughing, excessive Sneezing, coughing, excessive talking near evidence talking near evidence • Gloves and or masks should be changed Gloves and or masks should be changed

if contaminatedif contaminated

Protect the EvidenceProtect the Evidence Preserve evidence with proper Preserve evidence with proper

packagingpackaging Proper storageProper storage Use appropriate labelsUse appropriate labels

BIOHAZARD LABELSBIOHAZARD LABELSCase#, Initials, Descriptive label, Case#, Initials, Descriptive label, date packageddate packaged

Sign across your seal!!Sign across your seal!!

Evidence HandlingEvidence Handling Never collect evidence without Never collect evidence without

documenting the location, conditions, documenting the location, conditions, etc firstetc first

Sketches, photographs, detailed notesSketches, photographs, detailed notes The fewer people who handle The fewer people who handle

evidence, the betterevidence, the better Decreases chance of contaminationDecreases chance of contamination Assists in court admissibility hearing Assists in court admissibility hearing

Chain of CustodyChain of Custody A record of individuals who have had A record of individuals who have had

PHYSICAL possession of the evidencePHYSICAL possession of the evidence Critical in maintaining the integrity of Critical in maintaining the integrity of

the evidencethe evidence If DNA analysis results in a foreign If DNA analysis results in a foreign

DNA type, it may be necessary to DNA type, it may be necessary to identify persons who handled the identify persons who handled the evidenceevidence

Chain of Custody ComponentsChain of Custody Components Identifiers that describe the evidence Identifiers that describe the evidence

at the time it was foundat the time it was found• LocationLocation• PositionPosition• Date/Time of CollectionDate/Time of Collection

Packaging/Sealing informationPackaging/Sealing information

V isual/A lte rnateL ig ht S o urce Ne g ative

P o s itive

G e ne ralS wab b ing /Map p ing

(A P te s t) d o ne atanalys t d isc re tion

A P T e s t Ne g ative

Ne gativeP o s itive

Sperm searc hc onduc ted at

analy st's disc retion

P o s itive(no furthe r te s ting

req uire d )

P30at analys tdis c retion

P 3 0T e s t

S p e rm S e archcond uc te d

P o s itive(no furthe r

tes ting re q uire d )

P o s itive(no furthe r

te s ting re q uire d )

Ne g ative Ne g ative

If us ing A B A card sP S A -C heck fo r

ho ok e f fe c t; re -run

Ne g ative(no furthe r tes ting

re quire d )

Multi-Section CasesMulti-Section Cases

Many items need to go through other Many items need to go through other sections of the labsections of the lab

Common requests:Common requests:• Latent PrintsLatent Prints• Trace / MicroanalysisTrace / Microanalysis• FirearmsFirearms

Important to decide based on case, Important to decide based on case, which evidence has prioritywhich evidence has priority