Crime Scene And Trace Evidence Flashcards
1
Q
What is DNA profiling ?
A
process of extracting DNA to determine an individuals DNA characteristics
2
Q
Which cell stores the full genetic program of a person ?
A
Red blood cells
3
Q
How else, apart from identifying a suspect can DNA be used ?
A
To exonerate a suspect
4
Q
Where is DNA contained ?
A
In the nucleus
5
Q
What does DNA contain ?
A
Genetic instructions for development and functioning
6
Q
What is the structure of DNA ?
A
-double helix
-2 anti parallel strands wound around each other
-sugar phosphate backbone connected via hydrogen bonds
-complementary based pairs (A-T, G-C)
7
Q
Who pieced together all the information on DNA in 1952 ?
A
Watson and crick
8
Q
What are the four different bases of DNA ?
A
Adenine, Thymine, Guanine and Cytosine
9
Q
What are the components of a nucleotide ?
A
Sugar (deoxyribose), phosphate group and nitrogenous base
10
Q
What are histones ?
A
Proteins found in the nuclei which package and help order the DNA in nucelosomes
11
Q
What is chromatin ?
A
Complex of DNA and proteins that make up chromosomes ( the form in which the DNA is packaged within the nucleus)
12
Q
How is DNA as a euchromatin ?
A
Less condensed and more accessible
13
Q
How is DNA as a heterchromatin ?
A
More condensed and less accessible
14
Q
What is a chromosome ?
A
Thread like structure that consists of a long strand of DNA, carrying hundreds or thousands of genes, completely wound around and packaged with proteins
15
Q
What is a Karyotype ?
A
Total set of chromosomes
16
Q
What did Sir Alec Jeffreys discover ?
A
Mini satellites
17
Q
What is a mini satellite ?
A
Segments that vary in size and composition from individual to individual and had no apparent function
18
Q
What are variable number tandem repeats (VNTR) ?
A
Parts of the genome is made of short sequences of DNA which repeat in tandem
- the number of repeats for each unrelated individual is highly variable
19
Q
What are the two types of VNTR ?
A
Mini- satellites: 10-200 base pairs
Micro-satellites: 2-9 base pairs
20
Q
What is restriction fragment length polymorphism (RFLP ) ?
A
- genomic DNA is treated with restriction enzymes which cut DNA at a certain specific sequence of bases
-each restriction enzyme cuts in a unique restriction site
-results in several fragments of DNA in varying lengths
-placed on gel and an electric current is applied
-results in a pattern of bands
21
Q
What is used instead of RFLP ?
A
Short tandems repeats (STRs) as they’re more practical
22
Q
What is polymerase chain reaction (PCR) ?
A
-has 3 distinct stages: denaturation, annealing and extension
-denaturation: 96 degrees for 5-15s
-Annealing: 60 degrees for 35-60s
-Extension: 75 degrees for 5-60s
23
Q
How many cycles in PCR ?
A
25-30 depending on sample type and kit used
24
Q
Who invented PCR ?
A
invented in 1984 by Kary Mullins
25
What is SNP ?
When errors occur in replication and are not corrected
26
What is NGS ?
Full genome mapping which uses different methods of sequencing and can analyse multiple combinations of markers in tandem
27
What are short tandem repeats (STR) ?
STRs are highly polymorphic and are inherited from each parent
28
What does presumptive testing involve ?
-identifies substance
-often colorimetric
-sensitive, less specific
-fast, cheap, easy to
29
What does confirmatory testing involve ?
-identifies exact substance
-analytical method, highly specific
-time-consuming, expensive
-complex, requires specific setup
-stringent quality checks
30
What are the order of events for DNA profiling ?
-sample receipt
-extraction
-quantification
-amplification
-electrophoresis
-analysis
-interpretation
-reporting
-court
31
What are the key steps for the extraction and purification of DNA ?
-burst cell membrane to release DNA
-separate DNA from proteins and other cellular compounds
-cleaning the DNA
32
What are the most common methods for purification of DNA ?
-organic based
-silica based
-paramagnetic beads
33
What are the common methods for quantification of DNA ?
-UV spectrophometry
-fluorescence spectrophotometry
-hybridization
-real time PCR
34
What is quantification of DNA ?
Measurement of concentration of DNA
35
What PCR kit is used in the UK ?
DNA17
36
What are the different types of electrophoresis ?
Gel and capillary
37
How does gel electrophoresis work ?
Uses agarose or polyacrylamide gel
-DNA fragments separated by size
-Slower but can handle larger samples
-Visualized using UV light and dyes
38
How does capillary electrophoresis work ?
Uses thin glass capillaries filled with polymer
-Faster and more sensitive than gel
-Automated process
-Laser detection of fluorescently labelled DNA
39
What are the differences between gel and capillary electrophoresis ?
-Resolution: Capillary offers higher resolution
-Speed: Capillary is faster (30-60 minutes vs. hours)
-Sample size: Gel can handle larger samples
-Automation: Capillary is fully automated
40
What happens when an individual is arrested by the police ?
A DNA sample is taken and sent to an accredited lab who amplify and catalogue the sample
41
What samples does the national DNA database contain ?
-reference samples
-crime scene samples
-missing persons
-contamination elimination Db
-separate- staff elimination Db
42
What are the different types of DNA matches ?
-full
-partial
-familial
43
What are limitations of DNA evidence ?
-potential for contamination
-interpretation challenges with partial profile/ mixed samples
-importance of context in DNA evidence
-degradation of DNA
-transfer and persistence issues
44
What are ethical considerations in DNA profiling ?
-privacy concerns with databases
-familial searches and implications
-consent issues in mass screening
-potential for genetic discrimination
-ownership and storage of genetic information
-use of DNA for purposes beyond criminal investigation
45
What is IoT ?
Internet of things- any device that has the ability to connect to the internet
46
What is the fundamental problem of cyber security ?
Not understanding the problem
47
What is binary ?
Computers store data in 0 and 1s
48
What are the two types of encryption ?
Symmetric and asymmetric
49
What are the common uses of symmetric encryption ?
-Secure messaging apps
-file encryption software
-bitlocker
50
What are the common uses of asymmetric encryption ?
-secure email protocol
-digital signatures for documents authenticity and integrity
-secure key exchange and establishment of SSL/TLS protocol for secure websites
51
What are the three factors of authentication ?
- something you know (pin)
-something you have (device)
-something that proves who you are (fingerprint)
52
What is the role of police in a criminal enquiry ?
Police and Criminal Evidence Code of Practice paragraph 3.5, 1984
-The investigator should pursue all reasonable lines of inquiry, whether these point towards or away from the suspect.
53
What software is used to extract data from electronic devices ?
-belkasoft
-cellebrite
-grayshift
54
What are the ethical issues surrounding data access ?
-collecting data that is irrelevant
-retention of data
55
What is forensic entomology ?
The study of insects and other arthropods in legal context
56
What are the three main areas of entomology ?
-urban
-stored products
-medico-legal
57
What are the applications of medico-legal entomology ?
-fraud
-blackmail
-contamination of food stuff
-illegal importation
-delusory parasitosis
-criminal activity
58
When was entomology first used in the UK ?
1935- case of Dr Buck Ruxton
-killed his wife and her maid
-chopped up their bodies and wrapped them up in newspaper before disposing of them in Scotland
-larvae established when the bodies were deposited
59
What are necrophagous species ?
Feed on decaying flesh
60
What bug is the first to colonise the body ?
Blowflies
61
What feeds on the dry remains of the body ?
ham beetles
62
What are considered the secondary colonisers of the body ?
Rove beetles
63
What are omnivorous species ?
Feed on the body such as wasps and ants
64
What are adventive species ?
Use the body as a habitat
65
Why is blowfly larvae important ?
-most common on cadaver
-most rapid colonisers
-most accurate information regarding minimum time since death
66
What is the life cycle of a blowfly ?
-eggs
-1st instar larvae
-2nd instar larvae
-3rd instar larvae
-poparia containing puparia
-adult fly emerging from puparia
-adult blowfly
67
What is oviporous
Eggs laid which hatch into larvae
68
What is ovoviviporous ?
Eggs laid containing developed larvae
69
What is larviporous ?
Larvae laid (live)
70
What does measuring larval mass temp do ?
Help know which development stage larvae is in.
71
What is used to measure larval mass temp ?
Infrared data logger
72
How can you tell if 3rd instar larvae is feeding or post feeding ?
-if the food is still in the crop (stomach)
-if it was collected from the body or the surrounding area
73
What is maggot therapy ?
Using specific maggots in a bag to feed on dead skin to clean wounds
74
What is ADH ?
Accumulated degree hours
75
How is ADH calculated ?
Time x temperature
76
What can be used instead of ADH ?
ADD (accumulated degree days)
77
What is the purpose of a scene examination ?
- prove a crime has been committed
-identify/eliminate suspects
-establish identities of involved persons
-interpret the scenes
-link scenes to scenes
78
What is a scene strategy ?
Serious crimes tend to require a strategy to consider safety, minimising contamination and PPE
79
What are the considerations for a scene ?
-safety
-welfare
-PPE
-preservation
-areas of interest
80
What are the three main stages of a crime scene examination ?
-record
-recover
-add
81
What is done when recording during a crime scene examination ?
-crime scene notes
-photographs of the crime scene
-sketch
82
What is done when recovering during a crime scene examination ?
-recover evidence
-label all evidence as you go
83
What is done when adding during a crime scene examination ?
- add chemicals/ powders such as magenta flake for fingerprints
84
What would the steps be in a serious crime case ?
-PPE
-number of scenes
-resource allocation
-preservation
-trace recovery priorities
-other trace recovery
85
Can SOCOs cross scenes ?
No
86
What is Occam’s Razor ?
A principle that says the answer requiring the least assumption is probably the correct answer
87
What must be fuel be for a flaming fire ?
Gaseous
88
What is pyrolysis ?
Action of heat on most solid fuels- phase change and thermal decomposition of molecular structure to form vapours, gases and residual solid
89
What is vapour formation ?
Action of heat on flammable liquid fuel
90
What sort of process is combustion ?
Oxidation process
91
What is enthalpy ?
Heat of combustion and assumes complete combustion and that water is formed as a liquid not a gas
92
What is entropy ?
A measure of the degree of randomness, or disorder of the particles and energy in a system. An increase in the temperature will likely cause an increase in entropy
93
What is the tetrahedron of fire ?
For the chemical reaction to occur you need fuel, heat and oxygen
94
What are post fire indicators ?
Radiation, convection, conduction and direct burning
95
What is smouldering ?
Takes place at the molecular surface of the fuel and doesn’t require pyrolysis to produce fuel
96
What is extinction ?
remove an element of the fire tetrahedron
97
What are the forms of extinction ?
Smothering, starving, cooling and direct inhibition
98
What is looked at when investigating the fire ?
-physical evidence
-witness evidence
-historical evidence
-expert opinion
99
What is raptor persecution ?
Includes poisoning,shooting, trapping, habitat destruction and nest destruction
100
Wildlife and Countryside Act 1981
In the UK Birds of Prey are a protected species and therefore any criminal offences committed against them are covered under this act
101
How are different animals used ?
-traded for their parts
-for food
-for traditional Chinese’s medicines
-for the pet trade
-the tourist trade
102
Why is the collection of DNA crucial for prosecution of wildlife trade ?
As it helps confirm the type of species and its origin or distribution, shedding light on new trafficking routes and emerging trends.
103
What countries do animals and plants tend to be taken from?
Biodiverse countries such as Myanmar in SEA
104
What is CITES ?
An international agreement that countries sign up to and it sets limits for legal trade
105
What type of crime is illegal wildlife trade
Organised crime
106
What is the definition of organised crime ?
- when several people organise themselves into a network or chain in order to make money often by smuggling something along that chain or through that network
107
What are the different parts in response to illegal wildlife trade ?
- rangers
-rescue centres
-CITES
-police units
-intelligence-led crackdowns
-money laundering operations
-forensic science
108
What are the investigative questions asked in IWT ?
-what species is it ?
-where is it from ?
-which individual is it from ?
-who is this animal related to ?
-Is there evidence of pollution or of poisoning ?
-Is there evidence of deliberate harm ?
-How long has it been here ?
109
What is the law on elephant ivory ?
Listed on CITES appendix 1- no international trade allowed under CITES
110
What is the exception for trade of elephant ivory ?
-trade of some ivory products with exemption certificates from APHA
-have to be pre-1918 and of high cultural value
111
What are the different types of ivory ?
-African elephant
-mammoth tusk
-sperm whale tooth
-walrus tusk
112
What are different types of ivory products ?
-Roman die
-ivory figure
-elephant ivory cat
-tobacco jar
113
What is the morphology of ivory ?
-Schreger lines are formed from the shape that tusks grow at
-the angle they intersect is different
-a cross-sectional cutting of uncorked ivory tusk can be used for morphology
114
What database can you used to search for elephant species ?
BLAST
115
Why are seahorses listed on CITES ?
-before 2004, 19 million seahorses were taken from the seas per year
-threatening populations
116
What is the order of seahorse trade ?
- caught
-local shop owners consolidate catch
-buyers are mainly Asian experts
-all seahorses from a flight, ship or train that have crossed a border are in contravention of CITES
117
What is the NWCU ?
National Wildlife Crime Unit
118
What does the NWCU do ?
Set national priorities to focus efforts on the wildlife crimes of most concern
119
What is badger crime ?
-Badger setts are found in woods,
-Offenders dig down in to the setts
-Badgers are pulled out & dogs are released to fight with the badgers
-Both badgers and dogs are badly injured, and/or die.
-Driver is cruelty.
120
How does forensics aid in badger crime ?
Forensics can help to link spades, dogs and people to the crime scene…
….and or to the badger.
E.g.: human DNA or fingerprints on a spade + badger blood or sett soil on the other end
E.g. blood from an injured dog can be tested to see if any is from badgers.
121
How can forensics aid in egg collecting ?
-link people to eggs (fingerprinting)
-confirm the species
-link people to a crime scene or to the tools used for collecting, labelling and storing eggs
122
What is the most common type of bird to be stolen ?
Raptors (mainly eggs)
123
What are raptors taken for ?
Falconry
124
How can forensics aid in the stealing of birds and eggs ?
-link the suspect to the crime scene
-DNA confirming the species
125
What is the issue with microplastics ?
In the marine it is an emerging threat to aquatic wildlife
- a decrease in the number of offspring of copepods which are a major food source for many marine organisms
126
What are stable isotopes ?
Stable isotope analysis and chemical profiles can help in determining graphical origin and if species are captive bred
127
What does carbon C vary with ?
Photosynthesis processes
128
What does nitrogen vary with ?
Soil type and as we progress up the food chain
129
What is the effect of persistent organic pollutants ?
Have a detrimental effect on marine wildlife
130
What are POPs analysed by ?
-gas chromatography
-mass spectrometry
131
