Flashcards
Introduction to Forensic Science
Cards in this deck (81)
- 1Why the fundamental principles of crime scene management and investigation essential?- they act as a practical guide to action
- imposes a degree of order - 2Why are the fundamental principles not referred to as rules?In some situations, after careful consideration, they are not followed
- 3What are the "Six W's" of forensic investigation?Who
What
Why
When
Where
How - 4Why are the "Six W's" important?They form the central questions that need to be answered to solve a criminal enquiry.
They act as a framework for practical action. - 5What do the principles and practices form the basis for?A systematic, comprehensive and inquiring approach to the investigation of crime.
Allows insight, intuition and intelligence to be applied to investigate problems. - 6What other areas can be considered forensic science?Doping of athletes
Parentage testing
Investigation of environmental spills
authentication of works of art
Workplace drug monitoring
Public health matters - 7What is a crime scene?The scene of an incident irrespective of whether a criminal or illegal action has been established.
- 8What is crime scene investigation?Investigation begins with the response to a reported incident and ends when it is closed either with the assessment that there is no sound evidence of a crime being committed, or with the submission of one or more reports describing what was done, found and conclusions that were drawn.
It is a collaborative process that can involve police investigators, trained crime scene officers, specialist personnel and examining magistrates - 9What is crime scene management?The process of planning and conducting the searching of the scene.
- 10What is crime scene examination?The actual conduct of the securing, searching and interpretation of the scene.
- 11What is the starting point of a crime scene?The reporting of the incident. This is usually something seen by a routine police patrol or a call to the emergency services.
The critical first step in the examination of the crime scene is the action taken by the FOA. - 12What is the FOA?The police officers who respond to the notification. They can be known as first attending officers, first responders, or first officers attending.
They have to evalute the scene, ensure the safety of the victims and any others at the scene, and to determine whether or not a crime may have been committed. - 13What is the purpose of forensic science?To provide objective information on which reliable, evidence-based decisions can be made.
It deals with real or physical evidence, which is evidence based on the discovery and examination of material sources. - 14What is testimonial evidence?Someone's written or verbal account of something, for example, a police statement
- 15What is real evidence?Evidence based on the discovery and examination of material sources, for example, arising from the postmortem, examination of the crime scene, or searching the area.
It is more reliable than testimonial evidence, but it is not absolute or infallible.
It opens up a huge range of potential evidence that is unseen or unrecognised by the layperson. - 16What is the Locard Exchange Principle?Every contact leaves a trace.
The contact between people and objects, or people and other people will always result in the transfer of traces, such as hairs, fibres and DNA.
These will then provide evidence to link the accused to the scene and victims. - 17What are the issues with the Locard Exchange Principle?There are many issues, ranging from the epistemological concerns surrounding "every" to the practical issues of finding the transferred materials and how to interpret them.
- 18What is the link between real evidence and the Locard Exchange Principle?The Locard exchange principle is not a law of nature nor an ever present tool of the forensic scientist, but neither is it devoid of meaning. Real evidence can function as a silent witness and allow us to view things in context
- 19What are the core principles of crime scene examination?Control
Preserve
Record
Recover
Reconstruct - 20What is control?Control of access to the scene to prevent contamination (DNA), degradation (don't touch), change (moving objects or adding footwear marks)
- 21Who's access is controlled?People that do not need to be there:
general public, official personnel not actively involved in the investigation - 22Who's access is not controlled?People who need to be there:
safety emergency services, investigators and crime scene examinators - 23How are cordons used in more serious crimes?The conflicting needs of absolute control of the scene on the one hand and legitimate access to the area on the other may require the use of two cordons:
An outer cordon with morderate access control; A tightly controlled inner cordon around the focal point of the scene - 24What is a CAP?Common approach path. An access route to the scene that avoids any areas that mau have been used by the perpetrator to enter or leave the scene is identified, searched, recorded and cleared.
- 25What are the main points of control?Access to the scene must be controlled for the purposes of safety and security, integrity and legality
- 26Why are indoor scenes easier to preserve?The walls and doors provide a ready made cordon and access control. The integrity of the scene is protected against most environmental influences.
This assumes we are dealing with private property or smaller, discrete business premises, and that there are no substantial grounds involved in the crime. - 27What are substantial grounds that can be involved in crime?Access and egress or disposal of tools or weapon; no damage or malfunctioning of water supply, heating and lighting
- 28Why are outdoor scenes more difficult to control and preserve?Where would you place the cordon?
Why?
What about weather or traffic if on a road? - 29How are vehicles preserved?Usually associated with the outdoors, but to some extent cocoon the place of interest protecting it against environmental degradation.
- 30How is the scene preserved from contamination?White protective suits made from Tyvek (a strong breathable polyethylene fibre) worn with nitrile examination gloves, face marks and footwear covers.
Used to prevent any transfer of traces such as fibres and DNA between examiners and scene and between the scene and examiners.
Typically worn by teams at the scene of a major crimes. Whereas, examination of a volume crime scene would be conducted with few officers and minimal protective clothing, often only gloves and face masks. - 31How is the scene preserved from the environment?Erecting a portable tent to protect against the weather and intrusion.
- 32How is physical evidence preserved?Appropriate collection procedures and secure packaging. Secure means that the package is sealed in a way that is tamper evident and prevents loss to and contamination from the external environment during transport and storage to the laboratory.
- 33How is evidence collected and packaged?Trace materials invisible to the naked eye are protected by the manner in which the bulk item on which they are possibly located is handled.
Items such as clothing are carefully placed into evidence bags and sealed. Items from scene, victim and suspect are collected and packaged separately to prevent any possibilty of cross contamination. - 34What is taping?One of the best ways to collect evidence in the lab. The surface is dabbed with with clear adhesive tape and then fixed to a glass slide to be examined by microscopy.
- 35How can tyre marks or footwear impressions be preserved?Photography or casting depending on whether they are two or three dimensional
- 36How is spent ammunition collected?In a way that prevents leaving any marks, DNA or fingerprints, for example while wearing gloves and placing in a plastic jar or cardboard box
- 37How can finger prints be collected?A range of methods from dusting with powders to specialised chemical treatments
- 38How can biological evidence be preserved?if packed in plastic, it will undergo microbial degradation. Crime scene units in forensic biology laboratories have special drying areas where the items can be laid out, physically separated from each other, and dried in a gentle airflow.
A modern alternative is to use breathable evidence bags. - 39How is chemical evidence collected and preserved?These require special handling and will be examined by specially trained chemists who will have the equipment needed to collect and preserve the evidence.
- 40How is integrity viewed by the law?Courts require to be satisfied as to the authenticity of the items collected and tested before they will accept them and the derived evidence as exhibits in a trial.
This is achieved by a chain of custody which begins with the evidence log created during the examination of the scene. - 41What is the chain of custody?An unbroken chain authenticated by the signatures of those handling the items and the date and place it was in their possession.
Every item must have a record of what it is, where it was found, who has handled it in any way, when those things took place and where it has been between collection and production in court. - 42What are the legal aspects of evidence integrity?Admissibility conditional on proof of integrity. Achieved by evidence log. Establishes an unbroken chain of custody. Based on written/electronic signatures.
- 43Why is it important to record the scene?Records are made in order to create a permanent repository of reliable knowledge. It is essential requirement for legal purposes, communications, report writing and reconstruction.
Establishes a contemporaneous capture of the incident at the time of investigation. - 44How can the scene be recorded?Notes, plans, diagrams and witness statements supported by still or video photography and possibly other specialist means.
- 45How is photography used?The basic tool used to record the scene. Includes aspects such as general location, approach to scene, close-ups and items of interest.
- 46What is the structured approach taken for photography of the scene?Taking overlapping images that triangulate or quarter the general location and then approach to the scene itself. The photographic narrative is repeated at the scene with close-up images.
- 47What are items of interest?finger marks, footwear impressions, tool mark impressions and blood patterns.
- 48How are recording and recovery connected?The records can be regarded as a means to recovering the whole scene for scrutiny at a later time and place.
- 49What are the accepted search patterns?Search patterns are situational and the choice reflects the circumstances. Spiral for indoor and and lanes for larger outdoor areas.
Other search patterns include: grid, criss-cross, linear, zones or wheels - 50What is the role of a crime scene manager?Management of the technical aspects of scene examination and coordination with the SIO.
Responsible for the conduct of the technical aspects of the investigation and coordination with the SIO including assessment, planning and decreeing the forensic approach and the specific sequence of examinations in individual scenes. - 51What is the role of a crime scene examiner?The discovery and recovery of evidence such as DNA and fingerprints in major and volume incidents.
- 52What is the role of forensic scientists and specialists?Blood pattern analysis, marks examination and firearm examination.
- 53What is the role of a fingermark examiner?Most conduct at least basic fingermark enhancement and some conduct mark comparison. Advanced mark enhancement is more often than not the responsibility of forensic laboratory chemists.
- 54What are the specialised roles that may be required?Forensic Pathologist: examination of the body at the scene and post-mortem examination
Forensic Odontologist: examination and comparison of teeth indentation
Forensic Chemist: attend a scene involving a chemical, biological, radiological or nuclear incident
CBRN: attend a clandestine drug laboratory
Forensic Anthropologist: examines skeletal remains
Forensic Entomologists: estimation of time of death from infestation of corpses.
Fire and Explosion Investigators: determine the cause, origin and development of a fire - 55What?First and foremost about establishing criminal content or corpus delicti.
Also about ensuring that the reconstruction is detailed and accurate.
The sequence of events, accident or crime, real or staged?
Things left, removed, moved or alterned at the scene?
Possible motive of the persons involved? - 56Where?Did the crime take place? Did objects of interest at the scene come from? Else could they have been?
- 57How?About the modus operandi or method by which the crime was committed.
- 58Who?Human identity is central to criminal investigation. Victim, perpetrator and witness must be identified.
Recognition by DNA, fingerprints, facial recognition, tattoos and personal belongings.
Best when it is based on immutable characteristics intrinsic to the person: DNA/fingerprints - 59When?Deals with timing and the sequence of occurrence.
Estimation of time of death in the investigation of suspicious deaths and estimation of post-coital interval in investigation of rapes.
Produces an estimated range of the time. Recent deaths can be estimated from body temperature and degree of rigour mortis. Older remains can be estimated from progression of infestation. Post-coital interval can be estimated from amount of sperm recovered from vaginal swab. - 60Why?Motive, and can seldom be answered with real evidence.
- 61What are fingerprints used for?To check is an individual who is arrested is who they say they are and if they have come to police attention previously; eliminating individuals from criminal enquiries and to identify victims of mass disaster and terrorism.
Can also be used for general security in buildings and access to computers. - 62Where do fingerprints come from?Friction ridge skin found on the fingers, palms of the hands and soles of the feet. Origin of these patterns is genetic (with influence from non-genetic factors) and develop in the foetus in the womb.
- 63How can fingerprints be transferred?The patterns of ridges and furrows can be transferred in sweat and other substances to items when they are touched.
- 64What is a fingerprint?Refers to the impression taken from an individual as a record.
- 65What is a fingermark?Impressions recovered from crime scenes.
Also called latent prints. - 66What is the most common method of recovering latent prints?Fine powders applied with a brush. Finely-powdered aluminium is the most common one used and it adheres to the fatty components of the residue.
- 67What are the advantages of using powders?Simplicity and ease of application.
- 68How is the method of recovery decided?There is a wide range of techniques that can be used for detection and visualisation of finger marks, which depend on the nature of the surface on which the mark is deposited and the components in the resiude of the mark.
- 69How can lasers and ultraviolet light be used to detect finger marks?Used to promote fluorescence of marks which can then be photographed.
- 70How are fingerprints produced?From the contact between the ridges present on our fingers and a surface. The transfer is achieved by the deposition of the secretions from out glands associated with the ridges on our skin or by contaminants present on the finger surface.
- 71How are fingerprints formed in the womb?At 5/6 weeks EGA the foetus' hand will start to develop, with fingers developing at approximately 6/7 weeks EGA.
By 16 weeks EGA the mesenchymal tissue swirling is invisible as the growth of the hands has enveloped the pads.
In weeks 11-20 EGA the friction ridge development occurs with the volar pads providing the bedding for that development. Primary ridges on the dermis with fully formed ridge endings are the first to develop. Ridges will start to become visable from the apex of the finger, the top of the finger and the distal interphalangeal flexion crease. These occur at different speeds until they converge.
Between weeks 15-17 EGA secondary ridges start to develop and continues until week 24 EGA when the development of the dermis is complete. - 72What is powder suspension?Finger mark enhancement technique which is used on non-porous surfaces. It is a suspension of a coloured metal in a detergent solution. It is applied like paint then washed off with powder suspension remaining on the fingermark.
It is then left to dry before being photographed. - 73What are fingermark powders?Enhancement technique used on non-porous surfaces. Simply metallic dust applied using a powder brush. Some are magnetic and must be applied with a magnetic brush.
Aluminium powder best on plastic, black magnetic powder best on UPVC.
The powders adhere to the substances present in the finger mark. They are then photographed or lifted with fingermark tape. - 74What is Ninhydrin?A chemical solution used to nehance fingermarks on porous surfaces such as paper or cardboard. Reacts with amino acids present in the fingermark which cause it to produce a purple coloured mark. Recorded using photography or camera filters.
- 75What is cyanoacrylate?Technique used for non-porous surfaces. The vapour reacts with some fingermarks producing a white crystalline material on the ridges. This also stablises the mark. It can also be dyed using fluorescent dyes or powders can be applied.
- 76Why do visible fingermarks require no enhancement?They can be seen and generally recorded using photography. Commonly found deposited with the use of a contaminant such as blood, paint or dust.
- 77What are the three major glands responsible for fingermark deposits?Eccrine: found in highest densities in palms and soles
Apocrine: found in auxillary regions (armpits)
Sebaceous: localised in places with hair follicles
only eccrine and sebaceous glands contribute significantly to latent fingermark deposit - 78Why are porous substances better than non-porous substances for fingermark protection?Porous substances absorb the water-soluble part of the mark deposit within seconds, it cannot be simply rubbed away.
Non-porous substances do not absorb anything and can simply be wiped away. - 79What is ACE-V methodology?Analyse all variables influencing the fingermark.
Comparison
Evaluation
Verification - 80What are the three levels of detail?1. overall pattern
2. ridge characteristics
3. pores and edges of the ridges - 81Describe the components of blood.Erythrocytes: RBC, 5 million/micro-l of blood, red in colour and have no nucleus
Leukocytes: WBC, 9000/micro-l of blood, nucleated cells with roles in antibody production
Platelets: not cells, but small, colourless discs involved in blood clotting
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- 1 3rd Year Electives Flashcards on Introduction to Forensic Science, created by Caitlin M on 09/05/2018.
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