Serology& forensic science.bsc.3sem. pdf

Forensic science

1. Dr. Aamir Ali Khan
Assistant Professor
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2. ForensicScienceistheapplicationofscientificanalysisto
lawenforcement-ForensicToxicology,Document
examination,ForensicEntomology,etc
EveryForensicprocessstartsfromthecrimescene
Branchofforensicsciencethatdealswiththe
identificationandanalysisofbodilyfluids-Forensic
Serology
SerologyprecedesDNAAnalysisinaForensicLab
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3. Around1900,KarlLandsteinerdiscoveredthatthere
arefourdifferenttypesofhumanbloodbasedonthe
presenceorabsenceofspecificantigensfoundonthe
surfaceoftheredbloodcells.Thisleadtotheblood
groupsA,B,ABandO
In1940,LandsteinerandWeinerreportedthediscovery
oftheRhfactorbystudyingthebloodoftheRhesus
monkey
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4. Toknowhowsuspectedbodilyfluidsareidentifiedand
analyzedinForensicinvestigations
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5. Bodilyfluidsareliquidsthatoriginatefrominsidethe
bodyofhumans
Blood,Semen,Saliva
Bloodisthemostcommon
Biologicalstainsinthedriedstateare
reasonablystableandcanbedetectedmonths
oryearsafterbeingdeposited
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6. Isthefluidorstainblood,semen,saliva,etc?
Isitofanimalorhumansource?
Canitbelinkedtoaparticularspeciesorindividual?
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7. Visual/Physicalexamination-Normallybasedonthe
experienceoftheAnalyst.Thisisn'tadmissibleina
courtoflaw.Itcanonlygiveacluetotheanalyst
Presumptivetest:Thistesttellsthepresenceorabsence
ofasuspectedfluid.Cannotconfirmwhetherit’sfrom
animalorhuman.Eg.Blood
Confirmatorytest:Thistestgivesahighdegreeof
specificityforthebodyfluidinquestion.Eg.Human
blood
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8. UsetovisualizehiddenstainsinClothingandother
materials
Afterdetectionofstains,presumptivetestscanthenbe
performed
Adarkroomisneeded
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9. Somepresumptiveandconfirmatorytestscanreactto
thepresenceofothersubstancesasidethesuspected
fluidtogiveapositiveresult-Falsepositive
Somepresumptiveandconfirmatorytestscangivea
negativeresultasaresultofthesuspectedfluidbeing
insufficientforthetest-Falsenegative
Reagentorkitfailurecanalsogivefalsepositiveor
falsenegativeresultstoserologicaltests.Thisproblem
canbeavoidedwithtestingthereagentorkitona
knownbodilyfluid(+veControl)andareagentblank(-
vecontrol)
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10. BenzidineColourTest-Benzidineiscarcinogenic
sonotusedasoften.Benzidine+BloodStain+
Hydrogenperoxide=pinkcolor
Kastle-MeyerColourTest-Phenolphthalein+
Bloodstain+Hydrogenperoxide=pinkcolor
LuminolTest-Reactswithbloodtoproduce
luminescence(glow)
Hemastix:usetodetectbloodinurinebutisnow
widelyusetodetectbloodatthecrimesceneand
inthelab.ReagentstripswithTMB
(Tetramethylbenzadine)ends.TMBchangesfrom
orangetogreenwhenitcomesintocontactwith
blood
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12. AcidPhosphataseTest:Acidphosphatase
(AP)isanenzymesecretedbytheProstate
glandintoseminalfluid
SeveralchemicalsdetectAPinsemen-Alpha
Naphthylphosphate:turnspurplewithsemen
FastblueBDye:turnspurplewithsemen
4-methylumbelliferylphosphate:glowswith
semencontact
400timesAPinsementhananyotherbodily
fluid
Reactiontimeoflessthan30secs.meansyou
havefoundsemenandnotanyotherthing
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13. AmylaseTest:Oftheforensiclaboratories
thatperformpresumptivetestingfor
saliva,thedetectionofamylase,an
enzymefoundathighlevelsinsaliva,is
currentlythemostwidelyutilizedmethod
Amylaseisfoundinavarietyofbody
fluids;saliva,blood,urine,sweat,tears,
semen,breastmilk,feces,andvaginal
secretions,butismoreconcentratedin
saliva
PhabedasandRapidStainIdentificationof
HumanSaliva(RSID™-Saliva)Kitsused
bymanycrimelabsforpresumptiveand
confirmatorytests
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14. Jaffetest:Creatininecanserveasascreeningtestfor
urine
Toadropofstainextractonfilterpaper,addonedrop
ofPicricacidfollowedbyonedropof5%Sodium
hydroxide.Brown/orangecolorshowspresenceof
Creatinine
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15. PrecipitinTest:CombiningHumanantiserumand
humanbloodgivesagglutination
Thisprinciplehasbeenemployedintheproductionof
manycommercialkitsEg.HexagonOBTIKit
Requiresonlysmallamountofblood
Driedbloodstainsasoldas10-15yearswork
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17. ElectrophoreticMethod:Humanantibodiesand
bloodstainareplacedinwellsonelectrophoresisplate
Electricalcurrentisusedtomoveantibodiesand
antigenstowardseachother
Ifantibodiesandantigensmovetowardseachotherand
formalineofprecipitation,itishumanblood
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18. ProstateSpecificAntigen(PSAorp30)Test:Prostate-
specificantigen,orPSA,isaproteinproducedbycells
oftheprostategland
PSAisproducedfortheejaculate,whereit
liquefiessemenandallowsspermtoswimfreely
PSAispresentinsmallquantitiesintheserumofmen
withhealthyprostates
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19. WhenPSAisisolatedandinjectedintorabbits,an
immuneresponseistriggeredwhichproduces
antibodiesforthePSA(anti-PSA)
Serumisthencollectedfromtherabbit
Suspectedhumansemenisplacedinonewellofan
electrophoreticplateandanti-PSAisplacedinthe
oppositewell
Whenanelectricpotentialisapplied,theantigensand
antibodiesmovetowardeachother
Formationofavisiblelinemidwaybetweenthetwo
wellsshowsthepresenceofhumansemen.
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21. Identificationandanalysisofvariousbodilyfluidsis
paramountintheinvestigationofmanycrimes
Presumptiveandconfirmatorytestscanbeperformed
atthecrimescenewiththeadventofsimple-to-use
commercialkits
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22. http://www.bluestar-forensic.com/
https://www.salimetrics.com/
https://en.wikipedia.org/wiki/Prostate-
specific_antigen
http://www.cancer.gov/types/prostate/psa-
fact-sheet
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