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FORENSIC SCIENCE LABORATORY

FORENSIC SCIENCE LABORATORY. Dr Ajee Kuruvilla. Forensic science. Definitions Application of scientific knowledge to aid in the administration of justice Study and application of scientific examination and evaluation of evidence for legal purpose. Forensic science. Includes:

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FORENSIC SCIENCE LABORATORY

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  1. FORENSIC SCIENCE LABORATORY Dr Ajee Kuruvilla

  2. Forensic science Definitions • Application of scientific knowledge to aid in the administration of justice • Study and application of scientific examination and evaluation of evidence for legal purpose

  3. Forensic science Includes: • Forensic medicine (forensic pathology & forensic psychiatry) • Forensic toxicology • Forensic odontology • Forensic anthropology • Forensic police sciences (criminalistics, questioned documents, trace evidence, ballistics, criminology • Other specialties (polygraph, fingerprinting)

  4. Principles of Forensic science • Law of individuality Every object, natural or man made, has an individuality which is not duplicated in any other object • Principle of exchange (Locard’s principle) When 2 objects come in contact, there is always exchange of material • Law of progressive change Everything changes with the passage of time

  5. Principles of Forensic science • Principle of comparison Only the likes can be compared • Principle of analysis The analysis can be no better than the sample itself • Law of probability • Facts do not lie ‘Facts do not lie, men can and do’ facts can also be created !

  6. Functions of FSL • Examine, compare & evaluate physical evidence • Protection of innocent • Training of police investigators

  7. Divisions of FSL • Chemistry • Physics • Biology • Ballistics • Toxicology • Serology • Documents • Photography

  8. Lie detector (Polygraph) • Keeler polygraph, Stoelling deceptograph • Continuously records BP, pulse, respiration & electro dermal reaction • Fear stimulates sympathetic nervous system, resulting in physiological changes • Consent of subject essential • Leading questions asked • Relevant & irrelevant questions asked

  9. Lie detector (Polygraph) • One question every 20-25 sec, polygraph chart recorded in 3-4 minutes • Repetition of same test to check error • Experienced polygraph examiner can correctly detect truth / lie in 80- 90% • Offenders, suspects, complainants, witnesses, & informants examined • Useful in civil cases too

  10. Narcoanalysis (Truth serum) Close to unconsciousness, the subject is • Mentally incapable of resistance to questioning • Incapable of inventing lies to conceal guilt • Looses inhibition & becomes talkative • Depresses CNS, BP, slows heart rate • Susceptible to suggestion & reveals repressed feelings/ memories

  11. Narcoanalysis (Truth serum) Drugs used: • 0.5 mg scopalamine hydrobromide (s.c) • Sodium amytal/ sod pentothal 2.5 to 5% (iv) • 0.1 gm sod seconal + 15 mg morphine sulphate + 0.5 mg scopolamine hydrobromide (s.c)

  12. Hypnosis Helps in reviving memory of cooperative subjects

  13. Brain fingerprinting • Dr Lawrence A Farwel (USA) • Electro cap • Suspect questioned about crime along with visuals of crime scene • To stimulate his brain & encourage a reaction on a computer monitor

  14. Brain fingerprinting • Neuro impulses (brain waves, chemical responses) recorded • Intensity of brain wave shoots up whenever a question / visual stimuli matches the info stored in brain, if guilty • This is tracked and printed • Brain fingerprinting said to be more accurate than polygraph test

  15. QUALITATIVE ASSAYS Thin layer chromatography QUANTITATIVE ASSAYS Ultra violet spectrophotometry (UVS) Gas chromatography (GC) High performance liquid chromatography(HPLC) Mass spectrophotometry (MS) Radio-immuno assay (RIA) Enzyme mediated immuno assay technique (EMIT) Atomic absorption spectrophotometry (AAS) Neutron activation analysis (NAA)

  16. THANK YOU

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