FORENSIC SCIENCE LABORATORY Dr Ajee Kuruvilla Forensic science

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: • 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)

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

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 !

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

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

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

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

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

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)

Hypnosis Helps in reviving memory of cooperative subjects

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

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

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)

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