forensics lecture 1- introduction Flashcards
what is forensic science?
the application of scientific methods and techniques to matters under investigation by a court of law.
what is forensis?
in open court, public, from forum
what is the role of the forensic scientist?
-the recovery snd continuity of evidence
-analysis of evidence
-presentation of scientific findings in court
when are forensic scientists required?
-has a crime been committed?
-who is responsible?
-if the person responsible is traced, is there enough evidence to charge the person and support prosecution
what are the dates for the history of forensic science?
6th century = finger prints used for ID in china
8th century = first example accepted as evidence
1835 = first bullet comparison
1836 = first forensic toxicology
1901 = ABO blood groups discovered
1904 = locard’s exchange principle
1986 = Alec Jeffreys DNA profiling
what is forensic science like in England and Wales?
-Departments within police service
-Also private companies (e.g. Cellmark, LGC Forensics) and small scale practitioners
what is forensic science like in Scotland?
Scottish Police Authority (Ireland - FSNI)
for crime scenes, fingerprint, most lab-based forensic science
what is a forensic science regulator?
Currently Mr Gary Pugh
Ensures provisions of forensic science services are subject to appropriate quality standards
what is the locards principle?
every contact leaves a trace
what is physical fit?
Physical fit can prove beyond reasonable doubt the connection between a crime scene and a suspect
what is a trace?
a mark left by something; minute (tiny) amount
what is trace evidence?
very small amounts of material
Provide link
Locard’s Principle
how do you recover evidence?
-Shaking
-Brushing
-Taping
-Vacuuming
-Swabbing
-Hand Picking
-Extracting
-pipette/Swab
how do you target potential traces?
-Amount of material
-Persistence of material
-Finding the material
-Evidence value of the material
what are fibres?
any long thin flexible solid object with a high length to transverse cross-section area ratio
how does fibre analysis?
-Tapings
-Microscopy
-Thin Layer Chromatography
-Infrared spectroscopy
what is the test for semen?
-Microscopy
-Acid Phosphatase *
N-napthyl phosphate + ortho-dianisidine
-p30
-Semen is a good source of DNA
-Seminal fluid – sterile (no sperm)
what is the test for saliva?
Starch/Iodine
Salivary Amylase
Saliva may contain bacterial/cheek cells
what can hair analysis determine?
the classification such as Human/animal, Body area, Race, Artificial alteration, Damage
what are the parts of the hair?
the medulla in the centre, the Cortex in the middle and. surrounded by the cortex
what are the points to note about blood testing?
-Not entirely specific
-False reactions
-Obvious stains
-Haemoglobin enzyme/catalyst
-Red blood cells and platelets have no DNA
read the image for the screenshot of blood testing
what is the test for blood pattern analysis?
-To provide information regarding the sequence of events:
-Position of the victim
-Evidence of struggle
-Provide evidence to corroborate or refute statements made by those involved:
-Stain patterns on suspect’s clothing
-Stain patterns on victim/at scene
what are the types of blood pattern analysis?
passive, transfer, active
what is passive patterns?
due to gravity=
Drops, Drips, Pools, Clots, Shape affected by target surface texture
what is transfer patterns?
Wet bloody surface in contact with another surface produces a pattern=
Contact, Swipe/smear, Wipe, Smudge
what is projected?
-Arterial spurt/gush
-Cast off stains
Impact
low, medium, high velocity
Point of convergence is the centre point
what is glass analysis?
-Colour & Thickness
-Physical analysis
-Chemical analysis
– Scanning Electron Microspcope (SEM) & Energy Dispersive x-ray analysis
Information from crater shaped holes indicates direction of impact.
how do assess the significance of trace evidence?
-Extent of comparison
-Rarity of trace material
-Expectations
-Combination of evidence
-Alternative, innocent sources
-Contamination
how do you assess the reliability of trace evidence?
-Reputable
-Relevant circumstances
-Funding
what is the area of chemistry in forensics analysis?
-Footwear, tool mark and tyre analysis
-Paint and glass analysis
-Explosives analysis
what is the area of biology in forensics analysis?
-Blood, semen, other body fluids
-Hairs and fibres
-Blood pattern analysis
-DNA profiling
what is the area of documents in forensics analysis?
-Any item with writing
-Inceptive analysis
-Evidential
what is the area of toxicology in forensics analysis?
-Drugs or alcohol content in blood and urine samples in driving offences
-Presence of drugs in organs and tissues
-Identification of illegal drugs and their purity
