Forensic detection of seminal stains.pptx
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The document discusses several methods for detecting seminal stains, which are important for forensic investigations of sexual assault. Physical examination under UV light can detect fluorescent stains from semen. Chemical tests like the acid phosphatase test, Florence test, and Barberio's test detect compounds present in semen. Microscopic examination looks for sperm cells and staining characteristics. Electrophoretic methods analyze acid phosphatase and lactate dehydrogenase isoenzymes to differentiate semen from other body fluids. While no single test is perfect, using multiple confirmatory tests provides the most reliable results for seminal stain detection.
Forensic detection of seminal stains.pptx
- 1. Detection of Seminal Stains 6/6/2022 Toxicology & Forensic Serology 1 Dr Aamir Ali Khan PhD biochemistry Assistant Professor
- 2. Semen Toxicology & Forensic Serology 1 • Semen is afluid secretion containing cellular elements • Fluid formed in seminal vesicle and prostate • The seminal vesicle contain – High concentration of choline & lecithin • The prostate secrete – Acid phosphatase – Spermine 6/6/2022
- 3. Semen Toxicology & Forensic Serology 3 • The cellular element ;spermatozoa &epithelial cells formed by testes • Normal per ejaculation 2 to 5 ml semen • Around 100 million sperm/ml,80% motile • Slightly alkaline &liquefy in short time due to prostatic fibrinolysin 6/6/2022
- 4. Why Need SemenDetection Toxicology & Forensic Serology 4 • In charges of Rape & sodomy • Murder case suspected ,sexual assault • To detect stains on cloth or body of victim/accused • Bed clothes or where offense has been committed 6/6/2022
- 5. Material Collection • The stain fabric is cut &dried in the shade • Vaginal &high vaginal swab taken on sterile swab • Dried seminal fluid on thighs anal& perianal area taken by moist swab • Dry stain scraped into glass container by blunt scalpel • Pubic hair cut &preserve for further investigation Toxicology & Forensic Serology 5 6/6/2022
- 6. Semen Detection Method Physical Chemical Toxicology & Forensic Serology 6 Microscopic Electrophoretic 6/6/2022
- 7. Physical Examination Toxicology & Forensic Serology 7 • Garments often received, mud, blood, vaginal, urineetc • Clothes thoroughly examine under filter UV light • Urine, leucorrheal discharge show bright flourescence • The flourescence of Seminal stain is bluish white color 6/6/2022
- 8. Chemical Examination Toxicology & Forensic Serology 8 • Acid PhosphataseTest: – aquantitativetest – the amount of acid phosphatase is estimated in ameasured specimen, e.g.one square centimeter of stained material give positive reaction in old stain as well 6/6/2022
- 9. Chemical Examination Toxicology & Forensic Serology 9 • FlorenceTest: – A drop of watery solution of suspected stain when place on slide and let it dry ,place cover slip and adrop of florence reagent (KI+I+H2O) ,it will give dark brown crystal, choline periodide formed resembling haemin crystal ifseminal matter present – False negative: low choline content or decomposed stain – False positive result: other body tissue (except vagina) maycontained choline 6/6/2022
- 10. FlorenceTest Florence test https://www.stmaryscentre.org/application/files/9514/7697/8318/stmary sp resentation21.1.16.pdf, dated; 04-06-2021 1 0 Toxicology & Forensic Serology 6/6/2022
- 11. Chemical Examination 1 1 Toxicology & Forensic Serology • Barberio’sTest – The reaction depend upon spermine in semen – When fewdrops of barberios reagent(alcoholic soln of picric acid) added to spermatic fluid will produce yellow, needle shape &rhombic crystal of spermine picrate – Test is positive even without presence of spermatozoa – The limitation is pleomorphic nature of crystals 6/6/2022
- 12. Spermine picrate crystal Barberio test 1 2 Toxicology & Forensic Serology 6/6/2022
- 13. Chemical Examination 1 3 Toxicology & Forensic Serology • Creatine PhosphokinaseTest – Spermatozoa contain 2x high concentration of creatine phosphokinase compared to other body fluids – Level > 400 U/mlis almost diagnostic of seminal stain 6/6/2022
- 14. Microscopic Examination 1 4 Toxicology & Forensic Serology • Microscopic examination can be done directly or fixing and staining the smear • In case of fabric ,stained portion cut and soaked in acidulated water 1 hour to 4 hour • The fabric removed from soln and dabbed several time on clean slide gently • Slide can be seen directly under microscope or fixed & stained 6/6/2022
- 15. Microscopic Examination 1 5 Toxicology & Forensic Serology • Examine under low and high power objective • Human spermatozoa: – 50 micron long, 5 micron head, 3 micron breadth – Short body long filamentous tail – In stained specimen the hind part of head of sperm acquire deep blue tint while rest of head and tail deep red stained – Hard to recognize sperm ifits head falloff 6/6/2022
- 16. Toxicology & Forensic Serology 16 http://www.forensicindia.com/pgteaching/semen&seminalfluid.htm dated; 04-06- 2021 6/6/2022
- 17. Microscopic Examination 1 7 Toxicology & Forensic Serology • Disconnected head of sperm can be confused with microorganism like yeast, trichomonas vaginalis • As arule acomplete spermatozoa is necessary before giving positive result • The presence of Y chromosome in head of spermatozoa under fluorescent microscope help in identification 6/6/2022
- 18. Electrophoretic Method 1 8 Toxicology & Forensic Serology • Acid Phosphatase: – Acid phosphatase isoenzyme help differentiate seminal stain and stains from other sources on the basis of mobility – Semen can be detected even in absence of sperm, i.e.in azoospermic or vasectomised person 6/6/2022
- 19. Electrophoretic Method 1 9 Toxicology & Forensic Serology • Lactate Dehydrogenase: – the sperm specific iso-enzyme (LDHx), stable in stain for over four weeks – The iso-enzyme pattern of human semen is different from that of common animals – Positive results obtained in much larger number than is possible with microscopic examination 6/6/2022
- 20. Summary 2 0 Toxicology & Forensic Serology • Best sensitive test I-tartarate inhabitable acid phosphatase • Draw back, vaginal secretion also give positivetest • Florence test not sufficiently sensitive but can definitely rule out vaginal secretion • Microscopic Examination of Spermatozoa reliable & Specific • But may not be useful in very oldstains • LDH isoenzyme method is superior tomicroscopic detection of spermatozoa • But it has limitations to azoospermic & vasecomised person • Therefore is evident ,at least one confirmatory test should be usedin conjunction with I-tartarate acid phosphatase screening test 6/6/2022
- 21. Reference Toxicology & Forensic Serology 2 • Text book of Medical Jurisprudence,Forensic medicineandToxicology, BV Subrahmanym Seventh edition 6/6/2022