forensics case 12.05.05 focus: to be able to explain how we collect evidence

FORENSICS CASE FORENSICS CASE 12.05.0512.05.05

Focus:Focus:To be able to explain To be able to explain

how we collect how we collect evidence.evidence.

FORENSIC EVIDENCE FORENSIC EVIDENCE TYPESTYPES

•1./ Visual1./ Visual

•2./ Microscopical2./ Microscopical

•3./ Chemical3./ Chemical

•4./ Chromatographic4./ Chromatographic

•5./Using databases5./Using databases

•6./ Refractive index6./ Refractive index

THE FORENSIC THE FORENSIC PROCESSPROCESS•Observe scene – How?Observe scene – How?

•Collection of evidence – How?Collection of evidence – How?

COLLECTION OF COLLECTION OF EVIDENCEEVIDENCE•We need to ensure that forensic We need to ensure that forensic

evidence is not contaminated. evidence is not contaminated.

•To ensure that the following process To ensure that the following process has to occur:-has to occur:-

•1./ Examine the incident scene 1./ Examine the incident scene (observe and record)(observe and record)

•2./ Collect samples (label and seal in 2./ Collect samples (label and seal in bags)bags)

•3./Testing and analysing 3./Testing and analysing (Chemical tests, blood tests, etc)(Chemical tests, blood tests, etc)

•4./ Interpreting results (What 4./ Interpreting results (What facts are shown by results from facts are shown by results from tests, and what can be deduced.)tests, and what can be deduced.)

•5./ Prepare the report 5./ Prepare the report (accurate, clear and concise)(accurate, clear and concise)

•6./ Presenting evidence in 6./ Presenting evidence in court (Evidence indicates court (Evidence indicates probability rather than probability rather than proof.)proof.)

Collecting evidenceCollecting evidence

•AlcoholAlcohol :- Breathing into a :- Breathing into a breathalyser, or taking breathalyser, or taking samples of blood and urine samples of blood and urine and testing with potassium and testing with potassium dichromate.dichromate.

•Drugs – samples of powders Drugs – samples of powders are collected in plastic bags are collected in plastic bags and vials. Plant material is and vials. Plant material is placed in paper bags.placed in paper bags.

•Explosives – Residue Explosives – Residue collected from site of collected from site of explosions. Smells noted and explosions. Smells noted and accessories like blasting caps accessories like blasting caps collected.collected.

•Arson – Collecting samples of Arson – Collecting samples of porous materials from near porous materials from near source of fire. (eg:- Under the source of fire. (eg:- Under the settee.)settee.)

•Ballistics –Looking carefully Ballistics –Looking carefully at the bullets and cartridge at the bullets and cartridge cases to compare and find cases to compare and find gun from which bullet was gun from which bullet was shot. They also take casts of shot. They also take casts of bullet holes.bullet holes.

•Blood – Wet body fluids have to be Blood – Wet body fluids have to be air dried first, and packaged air dried first, and packaged separately in paper bag.separately in paper bag.

•Stains on surfaces – The item itself Stains on surfaces – The item itself is taken for analysis, or a swab is is taken for analysis, or a swab is taken with a cotton wool bud.taken with a cotton wool bud.

•Samples from suspects – are tubed Samples from suspects – are tubed and placed in the fridge for and placed in the fridge for analysis.analysis.

•Documents – The ink and Documents – The ink and signatures are compared signatures are compared along with paper type, etc. along with paper type, etc. These are collected and These are collected and bagged appropriately.bagged appropriately.

•Fibres and hairs – Visual Fibres and hairs – Visual searches, searches using searches, searches using different lighting and different lighting and microscopical searches are made microscopical searches are made for fibre collection.for fibre collection.

•Picking, taping, scraping and Picking, taping, scraping and vacuuming are used to collect vacuuming are used to collect evidence.evidence.

•Fingerprints – Dusting, Iodine Fingerprints – Dusting, Iodine fuming, Ninhydrin spray, fuming, Ninhydrin spray, Silver nitrate (both work with Silver nitrate (both work with sweat) and superglue fuming sweat) and superglue fuming are used.are used.

•Footprints and tyreprints – Footprints and tyreprints – Taking plastercasts and Taking plastercasts and photos.photos.

•Glass – Take samples of glass Glass – Take samples of glass in sealed bags from the area.in sealed bags from the area.

•Paint – Careful removal of Paint – Careful removal of paint is required so that all paint is required so that all layers of paint are removed.layers of paint are removed.

•Plastic – Collected by rubbing Plastic – Collected by rubbing sandpaper or emery board sandpaper or emery board over them. Details for over them. Details for different cars can be different cars can be collected from plastics used collected from plastics used for car bumpers.for car bumpers.

•Pollen – Collected using Pollen – Collected using cotton wool buds, and then cotton wool buds, and then viewed under a microscope.viewed under a microscope.

•Soil – Needs to be dried and Soil – Needs to be dried and then placed in individual then placed in individual paper bags. It should also be paper bags. It should also be taken from the area at the taken from the area at the same depth as the suspects same depth as the suspects shoe would go.shoe would go.

•Teeth – are collected and Teeth – are collected and bagged at the scene of a bagged at the scene of a crime. Teeth marks and bite crime. Teeth marks and bite are recorded using are recorded using photography and visual photography and visual examination.examination.

•How is contamination prevented on How is contamination prevented on each type of evidence during each type of evidence during collection?collection?

Alcohol, Drugs and Toxicology, Arson, Alcohol, Drugs and Toxicology, Arson, Ballistics, Blood, Documents, Ballistics, Blood, Documents, Explosives, Fibres, Fingerprints, Explosives, Fibres, Fingerprints, Footprints and tyreprints, Glass, Footprints and tyreprints, Glass, Hair, Paint, Plastic, Pollen, Soil and Hair, Paint, Plastic, Pollen, Soil and teeth.teeth.