This document discusses forensic DNA analysis and focuses on analyzing biological evidence such as blood and semen. It provides details on the composition of blood and its components like red blood cells, white blood cells, and platelets. Presumptive and confirmatory tests for identifying blood are described, including phenolphthalein, luminol, and Hematrace. The document also covers the composition of semen, identifying sperm under microscopy, and tests for semen like acid phosphatase and prostate specific antigen. Sources of biological evidence for DNA analysis and the importance of proper collection at crime scenes are highlighted.

1. Sarfaraz HussainSarfaraz Hussain
Roll#2054Roll#2054
Gcu FaisalabadGcu Faisalabad
TOPIC: Forensic DNA AnalysisTOPIC: Forensic DNA Analysis

2. Forensic DNA AnalysisForensic DNA Analysis
DNA is the Genetic MaterialDNA is the Genetic Material

3. Sources of Biological Evidence
Blood
Semen
Saliva
Teeth
Bone
Hair
Tissue
Feces
Urine
Skin Cells
Sweat

4. Critical to Locate EvidenceCritical to Locate Evidence
 It is important to have good crime sceneIt 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 inextract material from evidence. (BS in
Science)Science)
 Crime Scene analysts identify evidence atCrime Scene analysts identify evidence at
the crime itself. (BS in Criminal Justice)the crime itself. (BS in Criminal Justice)
 Forensic DNA analysts extract the DNAForensic DNA analysts extract the DNA
and perform the reactions and analyze theand perform the reactions and analyze the
results. (MS in science)results. (MS in science)

5. What is Blood?What is Blood?
 Slightly alkaline fluid made up ofSlightly alkaline fluid made up of
water, cells, enzymes, proteins,water, cells, enzymes, proteins,
glucose, hormones, organic andglucose, hormones, organic and
inorganic substancesinorganic substances
 Circulates throughout the bodyCirculates throughout the body
• Supplied nutrients and oxygen to theSupplied nutrients and oxygen to the
bodybody
• Removes wasteRemoves waste

6. Blood CellsBlood Cells
 Cells mature and differentiate intoCells mature and differentiate into
several classes of cellsseveral classes of cells
• Red blood cellsRed blood cells
• White blood cellsWhite blood cells
• PlateletsPlatelets

7. 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

8. Red Blood CellsRed Blood Cells

9. 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 externalVital source of defense against external
organismsorganisms
 White blood cells also clean up deadWhite blood cells also clean up dead
cells and tissue debris that wouldcells and tissue debris that would
otherwise accumulate and lead tootherwise accumulate and lead to
problems.problems.

10. Red and White Blood CellsRed and White Blood Cells
RBCs
WBCs

11. PlateletsPlatelets
 Irregularly-shaped, colorlessIrregularly-shaped, colorless
bodies produced in the bonebodies produced in the bone
marrowmarrow
 Their sticky surface lets them,Their sticky surface lets them,
along with other substances, formalong with other substances, form
clots to stop bleeding.clots to stop bleeding.
 Only active when damage occursOnly active when damage occurs
to the circulatory system walls.to the circulatory system walls.

12. PlasmaPlasma
 Liquid potion of bloodLiquid potion of blood
• Composed of water, proteins,Composed of water, proteins,
electrolyteselectrolytes
• Blood cells and platelets areBlood cells and platelets are
suspended in plasmasuspended in plasma
 Regulates osmotic pressureRegulates osmotic pressure
 The transport medium forThe transport medium for
 Glucose, lipids, hormones, clottingGlucose, lipids, hormones, clotting
factors, wastefactors, waste

13. SerumSerum
 Clear liquid that is left after bloodClear liquid that is left after blood
coagulatescoagulates
 Plasma without the clotting factorsPlasma without the clotting factors

14. Analyzing Genetic Variation inAnalyzing 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

15. Blood TypingBlood Typing
 All Blood groupsAll Blood groups
are determined byare determined by
the antigens onthe antigens on
their red bloodtheir red blood
cells.cells.
 Antibody-B reactsAntibody-B reacts
with A-antigen andwith A-antigen and
vice versavice versa
BloodBlood
Type:Type:
AntigensAntigens
on RBCson RBCs
Antibodies inAntibodies in
serumserum
AA AA Anti-BAnti-B
BB BB Anti-AAnti-A
ABAB ABAB NeitherNeither
Anti-A orAnti-A or
Anti-BAnti-B
OO NeitherNeither
A nor BA nor B
Both Anti-Both Anti-
A andA and
Anti-BAnti-B

16. 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 monkeysprotein also found in Rhesus monkeys
(85% of people are Rh +)(85% of people are Rh +)
 Combined with the ABO system,Combined with the ABO system,
the Rh factor can exclude suspectsthe Rh factor can exclude suspects
as well as include with some rareras well as include with some rarer
blood types.blood types.
 O+ 1 in 3 persons O- 1 in 15O+ 1 in 3 persons O- 1 in 15
personspersons

17. Presumptive TestsPresumptive Tests
 Presumptive Tests are used to tell if aPresumptive Tests are used to tell if a
sample is blood.sample is blood.
 Other presumptive tests can tell if aOther presumptive tests can tell if a
sample is human or primate blood.sample is human or primate blood.
 This is important to avoid wasting timeThis is important to avoid wasting time
trying to purify DNA from red paint andtrying 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 areact it with chemicals and look for a
color change.color change.

18. Phenolphthalein TestPhenolphthalein Test

19. Phenolphthalein TestPhenolphthalein Test
 LimitationsLimitations
• Sensitivity ~1/100,000 dilutionSensitivity ~1/100,000 dilution
• Lack of SpecificityLack of Specificity
 Chemical oxidants (bleach), vegetableChemical oxidants (bleach), vegetable
peroxidases cause reactionsperoxidases cause reactions
 Will not detect differences in animal orWill not detect differences in animal or
human bloodhuman blood
• StabilityStability
 Relatively stable if the reagents areRelatively stable if the reagents are
stored separately and refrigeratedstored separately and refrigerated

20. Leucomalachite GreenLeucomalachite Green

21. Leucomalachite GreenLeucomalachite Green
 Sensitivity ~1/1000 dilutionSensitivity ~1/1000 dilution
 Lack of specificityLack of specificity
• Chemical oxidants and vegetableChemical oxidants and vegetable
peroxidases cause a reactionperoxidases cause a reaction
• Will not detect differences in animalWill not detect differences in animal
or human bloodor human blood
 Stability- similar toStability- similar to
PhenolphthaleinPhenolphthalein

22. HemastixHemastix
 Reagent strips with TMB endsReagent strips with TMB ends
(Tetramethylbenzadine)(Tetramethylbenzadine)
 TMB changes from orange to greenTMB changes from orange to green
when it comes into contact withwhen it comes into contact with
bloodblood
 Used for occult blood in stoolUsed for occult blood in stool
 Somewhat quantitativeSomewhat quantitative
 Very sensitiveVery sensitive
 TMB dangerous

23. LuminolLuminol

24. LuminolLuminol
 How it worksHow it works
• The iron in hemoglobin acts as aThe iron in hemoglobin acts as a
catalyst to cause a reaction betweencatalyst to cause a reaction between
the luminol and Hthe luminol and H22OO22
• Luminol loses nitrogen and hydrogenLuminol loses nitrogen and hydrogen
and gains oxygenand gains oxygen
• This results in 3-aminopthalate whichThis results in 3-aminopthalate which
is energized and emits lightis energized and emits light

25. LuminolLuminol
 Sensitivity ~10Sensitivity ~10-8-8
(most sensitive(most sensitive
presumptive)presumptive)
 SpecificitySpecificity
• Bleach, metals, chemical oxidants,Bleach, metals, chemical oxidants,
plant peroxidases light up too.plant peroxidases light up too.
• Will not differentiate animal andWill not differentiate animal and
human bloodhuman blood
 Very unstable ~4 hours for theVery unstable ~4 hours for the
mixturemixture
 Mostly used at crime scenesMostly used at crime scenes

26. ABAcard HematraceABAcard Hematrace
 Confirmatory test (shows that it isConfirmatory test (shows that it is
human or primate blood, since thehuman 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)

27. ABAcard HematraceABAcard Hematrace

28. SemenSemen
 Most common crime with DNAMost common crime with DNA
evidence is sexual assaultevidence is sexual assault
 Sperm have DNA which can be wellSperm have DNA which can be well
preserved if dried on cloth.preserved if dried on cloth.

29. Semen CompositionSemen Composition
 Semen is a fluid of complexSemen is a fluid of complex
composition, produced by the malecomposition, 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

30. Seminal PlasmaSeminal Plasma
 Composed of salts, sugars, lipids,Composed of salts, sugars, lipids,
enzymes, nutrients, proteins,enzymes, nutrients, proteins,
hormones, basic amines (spermine),hormones, basic amines (spermine),
P30, flavinsP30, flavins
 Enzymes- Acid PhosphataseEnzymes- Acid Phosphatase
 P30 ( a prostate specific protein used inP30 ( a prostate specific protein used in
prostate cancer tests)prostate cancer tests)
 FlavinsFlavins
 The components originate from severalThe components originate from several
sources, including seminal vesicles andsources, including seminal vesicles and
the prostate glandthe prostate gland

31. Sperm CellsSperm Cells
 Sperm are the male reproductiveSperm 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,In humans, the head is a tiny disc,
about 4.5 um long and 2.5 um wideabout 4.5 um long and 2.5 um wide
• The tail is about 40 um long, and isThe tail is about 40 um long, and is
rapidly lost in ejaculaterapidly lost in ejaculate

32. 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 largerbut are about three times larger
than human spermthan human sperm
 Other animals have differentlyOther animals have differently
shaped spermshaped sperm
 Situations?Situations?

33. 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 ofIt is common practice to visually assess items of
evidence under UV light to located possible semen stainsevidence under UV light to located possible semen stains
 What fluoresces in semen?What fluoresces in semen?
• The intensity of the fluorescence can be affected by theThe intensity of the fluorescence can be affected by the
substrate, concentration of the stain, and other bodysubstrate, concentration of the stain, and other body
fluidsfluids
 Identified on crime scene or in lab by EvidenceIdentified 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

34. Presumptive test: SemenPresumptive test: Semen
 Acid Phosphatase TestAcid Phosphatase Test
• Human semen contains high concentrations ofHuman semen contains high concentrations of
acid phosphatase (AP), which can therefore beacid phosphatase (AP), which can therefore be
the basis of the screening testthe basis of the screening test
• While AP is detected in high concentrations inWhile AP is detected in high concentrations in
semen, it can also be detected in other bodysemen, it can also be detected in other body
fluidsfluids
 False positivesFalse positives
• Vaginal acid phosphataseVaginal acid phosphatase
• Fecal materialFecal material
• Plant matterPlant matter
• Spermicides (orange)Spermicides (orange)

35. Confirmatory Tests: SemenConfirmatory Tests: Semen
• P30 identificationP30 identification
 Found in semenFound in semen
• MicroscopyMicroscopy
 Identification of spermIdentification of sperm

36. 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 instrumentalLiquefies semen and is instrumental
in dissolving the cervical mucous capin 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)

37. P30 TestP30 Test

38. Sperm IDSperm ID
 Confirm the presence of semen byConfirm the presence of semen by
microscopically identifying spermmicroscopically identifying sperm
cellscells
 Most common staining method isMost common staining method is
Kernechtrot picroindigocarmineKernechtrot picroindigocarmine
stain- Alsp called Christmas Treestain- Alsp called Christmas Tree
StainStain
 Prepared or commercially suppliedPrepared or commercially supplied

39. Human

41. Dog

42. Collection of Hair SpecimenCollection of Hair Specimen

43. HairHair
 Composed of cylindrical structures orComposed of cylindrical structures or
shafts made up of tightly compacted cellsshafts made up of tightly compacted cells
that grow from folliclesthat grow from follicles
 Diameter ranges from 15-120Diameter 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 DNARoot material can be used for nuclear DNA
testingtesting
 Shaft material can be used for someShaft material can be used for some
mitochondrial DNA testing too.mitochondrial DNA testing too.

44. Hair RootsHair Roots

Pulled Forcibly Removed Shed

45. Tip of the ShaftTip of the Shaft

Burned Cut Razored
Split

46. HairHair
Basic Evaluation StepsBasic Evaluation Steps
1.1. Determine if the sample is a hairDetermine if the sample is a hair
2.2. Determine if the hair is of human originDetermine if the hair is of human origin
3.3. Determine if the hair has root material-Determine if the hair has root material-
suitable for nuclear DNA analysissuitable 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 fordetermine if the hair is sufficient in size for
mtDNA analysis (2-3cm)mtDNA analysis (2-3cm)

47. HairHair
DNA analysis of hair is a destructiveDNA analysis of hair is a destructive
technique and results in thetechnique 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 belength, shape, and texture should be
noted in the case file for futurenoted in the case file for future
reference prior to DNA analysisreference prior to DNA analysis
 Notes and digital imagesNotes and digital images

48. SalivaSaliva
Colorless fluid secreted by 3 glandsColorless fluid secreted by 3 glands
in the mouthin the mouth
• Sublingual, submandibular, andSublingual, submandibular, and
parotidparotid
• Saliva from parotid glands containSaliva from parotid glands contain
amylases, enzymes, which aid in theamylases, enzymes, which aid in the
digestion of carbohydratesdigestion of carbohydrates
• Saliva is composed of electrolytes,Saliva is composed of electrolytes,
enzymes, mucusenzymes, mucus

49. SalivaSaliva
Screening for saliva is based onScreening for saliva is based on
detection of high levels of amylase indetection of high levels of amylase in
the samplethe sample
• It is not a confirmatory test; amylase isIt is not a confirmatory test; amylase is
found in other body fluidsfound 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 isThe concentration of amylase in saliva is
variable among individual; if amylase isvariable among individual; if amylase is
not detected in a sample it does notnot detected in a sample it does not
mean saliva is not presentmean saliva is not present

50. SalivaSaliva
 UV light can be used to aid inUV light can be used to aid in
locating saliva stainslocating saliva stains
• The intensity of the fluorescence can beThe intensity of the fluorescence can be
affected by the substrate, concentrationaffected by the substrate, concentration
of the stain, and other body fluidsof the stain, and other body fluids
• Saliva does not fluoresce as intensely asSaliva does not fluoresce as intensely as
semensemen

51. AmylaseAmylase
 One of the earliest tests for amylase wasOne of the earliest tests for amylase was
the starch-iodine testthe starch-iodine test
 Iodine solutions cause starch to turn aIodine 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 theThe presence of amylase causes the
disappearance of the blue color (due todisappearance of the blue color (due to
hydrolysis of the starch) and can be usedhydrolysis of the starch) and can be used
an indicator for the presence of amylasean indicator for the presence of amylase

52. PhadebasPhadebas ®®
TestTest
http://www.uni-wuerzburg.de/ddch/liquits/Amylasedirekt.jpg
Positive testNegative test

53. Vaginal SecretionsVaginal Secretions
 Vaginal secretions are a complexVaginal secretions are a complex
mixture of cells and secretionsmixture of cells and secretions
 There is no confirmatory test toThere is no confirmatory test to
identify vaginal secretionsidentify vaginal secretions
 Several screening tests based onSeveral screening tests based on
microscopy have been proposed.microscopy have been proposed.

54. Vaginal SecretionsVaginal Secretions
 Vaginal epithelial cells are large, and manyVaginal epithelial cells are large, and many
contain glycogen (a polysaccharide) whichcontain glycogen (a polysaccharide) which
can be demonstrated by staining withcan be demonstrated by staining with
iodine in the form of a solution or exposingiodine in the form of a solution or exposing
to iodine vapor.to iodine vapor.
 The presence of glycogenated cells isThe presence of glycogenated cells is
variable depending on the stage of thevariable depending on the stage of the
woman’s cyclewoman’s cycle
 Glycogenated cells can be found in otherGlycogenated cells can be found in other
body secretions (i.e. oral, anal)body secretions (i.e. oral, anal)

55. Fecal MaterialFecal Material
 Feces are food residues passed afterFeces are food residues passed after
completion of travel through thecompletion of travel through the
digestive systemdigestive system
 Has a characteristic odor mainly dueHas a characteristic odor mainly due
to skatole, an organic compound thatto skatole, an organic compound that
occurs naturally in fecesoccurs naturally in feces

56. Fecal MaterialFecal Material
MicroscopyMicroscopy
 Microscopy has been used to identify fecalMicroscopy has been used to identify fecal
materialmaterial
• Looking for undigested residues of foodLooking for undigested residues of food
materialmaterial
 Chemical TestsChemical Tests
 Detection of urobilinogen, a bile pigmentDetection of urobilinogen, a bile pigment
excreted in feces, which may be detectedexcreted in feces, which may be detected
using its fluorescent reaction to Edelman’susing its fluorescent reaction to Edelman’s
reagentreagent

57. UrineUrine
 No confirmatory tests for the presenceNo confirmatory tests for the presence
of urineof urine
 Urine stains fluorescent under ultravioletUrine stains fluorescent under ultraviolet
lightlight
• This can be useful for locating stains prior toThis can be useful for locating stains prior to
chemical testingchemical testing
 Has a characteristic odorHas a characteristic odor
 Contains a large amount of urea, aContains a large amount of urea, a
chemical byproduct of normal metabolicchemical byproduct of normal metabolic
processes in the bodyprocesses in the body
• Identification of high levels of urea can serveIdentification of high levels of urea can serve
as a screening test for urine in fluids oras a screening test for urine in fluids or
stainsstains

58. UrineUrine
 Contains creatinine, which is a breakdownContains creatinine, which is a breakdown
product of creatine (an important part ofproduct of creatine (an important part of
muscle)muscle)
 Over time, the creatine molecule graduallyOver time, the creatine molecule gradually
degrades to creatininedegrades to creatinine
 Creatinine is a waste product that isCreatinine is a waste product that is
excreted from the body entirely by theexcreted from the body entirely by the
kidneyskidneys
• Identification of creatinine can serve as aIdentification of creatinine can serve as a
screening test for urine in fluids or stainsscreening test for urine in fluids or stains

59. CreatinineCreatinine
Jaffe TestJaffe Test
 One of the oldest tests for theOne of the oldest tests for the
detection of creatinine-1886detection of creatinine-1886
 Creatinine forms a red compoundCreatinine forms a red compound
with picric acid (Jaffe test)with picric acid (Jaffe test)

60. Teeth and BoneTeeth and Bone
 DNA can be extracted from nucleated cellsDNA 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 theTeeth are drilled in the lab and the
material is extracted and DNA ismaterial is extracted and DNA is
extracted.extracted.
 Bone is drilled out and DNA is extractedBone is drilled out and DNA is extracted
 Teeth and bones are best tissue for DNATeeth and bones are best tissue for DNA
analysis from skeletal remains.analysis from skeletal remains.

61. Touch EvidenceTouch Evidence
 Epithelial cells that have been transferredEpithelial cells that have been transferred
from the person to the evidence viafrom the person to the evidence via
“touching”“touching”
 These samples tend to have low amountsThese samples tend to have low amounts
of DNAof DNA
 Would expect body fluid stains to haveWould expect body fluid stains to have
more DNA than touch evidencemore DNA than touch evidence
 Body fluid comparison:Body fluid comparison:
• Undiluted semen (with sperm) stain > bloodUndiluted semen (with sperm) stain > blood
stainstain
• Both blood and semen > saliva stainBoth blood and semen > saliva stain
• Body fluids > wear area stain (armpits, collarBody fluids > wear area stain (armpits, collar
of a shirt)of a shirt)

62. Case ProcessingCase Processing
Includes:Includes:
Location and Collection of EvidenceLocation and Collection of Evidence
 Collection TechniquesCollection Techniques
 Preservation of EvidencePreservation of Evidence
 Packaging and StoragePackaging and Storage
 Documentation-Chain of CustodyDocumentation-Chain of Custody
 Casework AnalysisCasework Analysis

63. Location and Collection of EvidenceLocation and Collection of Evidence
Evidence:Evidence:
 Physical Evidence - any tangiblePhysical Evidence - any tangible
object that can connect an offenderobject that can connect an offender
to a crime scene, an offender to ato 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 physicalBiological Evidence is physical
evidenceevidence - but is not always visible- but is not always visible
to the naked eyeto the naked eye

64. Sources of Biological Evidence
• Blood
• Semen
• Saliva
• Urine/Feces
• Hair
• Teeth/Bone
• Tissue
• Cells

65. 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 sceneAll persons who had access to a crime scene
should be documentedshould be documented
• May be necessary to collect samples fromMay be necessary to collect samples from
these individualsthese individuals

66. Actions to AvoidActions to Avoid
 Touching any areas/items whereTouching any areas/items where
DNA may existDNA may exist
 Touching your face, nose, hair, andTouching your face, nose, hair, and
mouth when collecting andmouth when collecting and
packaging evidencepackaging evidence
 Sneezing, coughing, excessiveSneezing, coughing, excessive
talking near evidencetalking near evidence
• Gloves and or masks should be changedGloves and or masks should be changed
if contaminatedif contaminated

67. Protect the EvidenceProtect the Evidence
 Preserve evidence with properPreserve evidence with proper
packagingpackaging
 Proper storageProper storage
 Use appropriate labelsUse appropriate labels
BIOHAZARD LABELSBIOHAZARD LABELS
Case#, Initials, Descriptive label,Case#, Initials, Descriptive label,
date packageddate packaged
 Sign across your seal!!Sign across your seal!!

68. Evidence HandlingEvidence Handling
 Never collect evidence withoutNever collect evidence without
documenting the location, conditions,documenting the location, conditions,
etc firstetc first
 Sketches, photographs, detailedSketches, photographs, detailed
notesnotes
 The fewer people who handleThe fewer people who handle
evidence, the betterevidence, the better
 Decreases chance of contaminationDecreases chance of contamination
 Assists in court admissibility hearingAssists in court admissibility hearing

69. Chain of CustodyChain of Custody
 A record of individuals who have hadA record of individuals who have had
PHYSICAL possession of the evidencePHYSICAL possession of the evidence
 Critical in maintaining the integrity ofCritical in maintaining the integrity of
the evidencethe evidence
 If DNA analysis results in a foreignIf DNA analysis results in a foreign
DNA type, it may be necessary toDNA type, it may be necessary to
identify persons who handled theidentify persons who handled the
evidenceevidence

70. Chain of Custody ComponentsChain of Custody Components
 Identifiers that describe the evidenceIdentifiers 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

71. V is u a l/ A lt e r n a t e
L ig h t S o u r c e
N e g a t iv e
P o s it iv e
G e n e r a l
S w a b b in g / M a p p in g
( A P t e s t ) d o n e a t
a n a ly s t d is c r e t io n
A P T e s t N e g a t iv e
N e g a t iv eP o s it iv e
S p e r m s e a r c h
c o n d u c te d a t
a n a ly s t's d i s c r e ti o n
P o s i t iv e
( n o f u r t h e r t e s t in g
r e q u i r e d )
P 3 0
a t a n a ly s t
d is c r e t io n
P 3 0
T e s t
S p e r m S e a r c h
c o n d u c t e d
P o s i t iv e
( n o f u r t h e r
t e s t in g r e q u i r e d )
P o s it iv e
( n o f u r t h e r
t e s t in g r e q u ir e d )
N e g a t iv e
N e g a t iv e
I f u s i n g A B A c a r d s
P S A - C h e c k f o r
h o o k e f f e c t ; r e - r u n
N e g a t iv e
( n o f u r t h e r t e s t in g
r e q u ir e d )

72. Multi-Section CasesMulti-Section Cases
 Many items need to go through otherMany 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