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forensics Flashcards

1
Q

what does a forensic scientist do

A

give impartial evidence in relation to the law by carrying out a variety of analytical measurements which are used to discriminate between individuals/groups

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2
Q

what does the extent of forensic analysis carried out depend on

A

the scientists experience
time pressures
costs

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3
Q

when is forensic science required

A

when a crime has been committed and you are trying to finds the responsible person
need to determine whether death was by natural causes or not

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4
Q

when and where did forensics begin

A

in the 6th century with use of finger prints in china

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5
Q

what are the 4 main areas for forensic science and give examples of work carried out in each

A

biology - biological sample testing
chemistry - firearm residues, object analysis
toxicology - drugs and alcohol
documents - anything with writing - inceptive analysis

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6
Q

what are the 7 types of forensic scientist

A 
pathologist
entomologist
dentist
psychologist 
scene of crime officer 
archaeologist 
anthropologist
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7
Q

what are the 2 basic principles in forensic science

A

locard’s principle

physical fit

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8
Q

what is locard’s principle

A

every contact leaves a trace - either leave something behind or take something away

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9
Q

what is physical fit

A

physical fit can prove beyond reasonable doubt the connection between a crime scene and a suspect
evidence fit together

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10
Q

what is the chain of custody/evidence

A

preserve the scene
search for material of evidential value
all evidence must be packaged and labelled correctly
safe storage and transmission to the lab
evidence needs to be handled properly
can be acquitted if evidence isn’t collected properly

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11
Q

what is trace evidence

A

provides a link between suspect and victim/locus

very small amounts of material

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12
Q

what are the 2 types of trace evidence

A

reactive trace

inceptive trace

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13
Q

what is reactive trace

A

know something about the suspect and looking for links

e.g. know the suspect was wearing a green hat, look for fibres on victim

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14
Q

what is inceptive trace

A

don’t know anything about the suspect but find green fibres on victim, find link to suspect

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15
Q

what are some of the difficulties looking for trace material

A

the amount of material often limited
need to know where to look
need to estimate the evidential value of the material

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16
Q

give examples of how we recover evidence

A 
shaking
brushing 
taping 
vacuuming 
swabbing 
hand picking 
extracting 
pipette/swab
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17
Q

how can we analyse glass and what do we get from it

A

colour and thickness
physical analysis - refractive index - the further away from the average (1.5) the rarer it is
chemical analysis - scanning electron microscope and energy dispersive X ray analysis
information from crater shaped holes indicate direction of impact

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18
Q

what is a fibre

A

any long thin flexible solid with a high length to transverse cross section area ratio and can be man made or natural

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19
Q

what are methods of fibre analysis

A

microscopy
tapings
TLC
IR spec

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20
Q

what are the components of hair

A

medulla (sometimes absent), cortex (made of cortical cells) and cuticle (made of scale cells)

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21
Q

how can we use hair for classification

A 
human or animal hair testing 
what part of the body is it from 
can we determine race 
is it dyed - artificial alteration 
damage - are roots present
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22
Q

why can hair have limited evidential value

A

if the roots are absent there is not much we can infer from it
if the roots are present we can determine blood groups and possibly DNA profiles

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23
Q

how can hairs be useful for toxicology

A

drugs in hairs can affect length - we can determine the extent of drug use and when it stopped if it did

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24
Q

how can we characterise blood

A 
human or animal 
what type of animal
if human blood what type 
sex 
race
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25
Q

what are some points to note about preliminary testing for drugs

A

not entirely specific
false reactions
rbcs and platelets have no DNA

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26
Q

what are the 3 tests we can do for bloods

A

LMG
phenolphthalein
luminol

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27
Q

what is the luminol test

A

luminol + hydrogen peroxide –> 3 aminophthalate (light given off)

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28
Q

what is the LMG test

A

LMG + hydrogen peroxide –> oxidised LMG (green)

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29
Q

what is the phenolphthalein test

A

phenolphthalein + hydrogen peroxide –> phenolphthalein oxidised (red)

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30
Q

what preliminary testing can we use for semen

A

microscopy
acid phosphatase
p30
DNA profiling - semen is a good source of DNA but seminal fluid contains no DNA unless it contains skin cells

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31
Q

what preliminary testing can we use for saliva

A

starch/iodine
salivary amylase
saliva may contain bacterial/cheek cells

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32
Q

what is the purpose of blood pattern analysis

A

to provide information regarding the sequence of events: the position of the victim and evidence of struggle
provide evidence to corroborate or refute statements made by those involved

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33
Q

what are the 3 types of blood pattern

A

passive
transfer
projected/active

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34
Q

what is blood stain pattern analysis

A

examination of shapes, location and distribution patterns of blood stains in order to provide an interpretation of the physical events which gave rise to the origin

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35
Q

what is a passive pattern

A 
due to gravity:
drops 
drips 
pools
clots
shape effected by target surface texture
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36
Q

what is a transfer pattern

A

wet bloody surface on contact with another surface produces a pattern

  • contact
  • swipe/smear
  • wipe
  • smudge
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37
Q

what is a projected pattern

A

arterial spurt/gush
cast of stains
can infer impact
point of convergence

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38
Q

what factors do we need to consider when looking at the significance of trace evidence

A
  • extent of comparison
  • rarity of trace material
  • expectations
  • combination of evidence
  • alternative innocent sources
  • contamination
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39
Q

what is alcohol

A

ethanol is clear, colourless and miscible with water

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40
Q

what is alcohol produced by

A

fermentation from grapes and cereal grains

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41
Q

what are the steps in absorption and distribution of alcohol

A

mouth
GI tract
circulatory system –> brain, kidneys, lungs and liver

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42
Q

what % of alcohol is absorbed in the stomach

A

20%

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43
Q

what % of alcohol is absorbed in the small intestine

A

80%

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44
Q

what factor can effect the rate of alcohol absorption

A
  • quantity of alcohol consumed
  • concentration of alcohol
  • contact time in GIT
  • food - food intake delays the transfer to the small intestine which in turn delays absorption
  • stomach emptying - changes how long it takes to move to the small intestine
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45
Q

the distribution of alcohol is rapid/slow

A

rapid

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46
Q

alcohol is distributed to all organs and body compartments but how are the proportions decided

A

by the organ/compartments water concentration - the higher the water content the more alcohol can be absorbed because alcohol is miscible with water

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47
Q

most organs and fluids are in a constant equilibrium with ………..

A

blood

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48
Q

list the affects associated with different alcohol levels

A 
mg/100ml 
under 50 - not obvious, talkative 
50-100 - slurred speech, coordination loss 
100-150 - loss of gait, possible nausea 
150-200 - nausea, non- cooperative 
200-300 - probable coma 
300-400 - coma, impaired respiration 
400+ - death may ensue from respiratory paralysis
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49
Q

what % of the alcohol consumed is metabolised

A

90%

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50
Q

what are primary and secondary alcohols oxidised to

A

aldehydes then carbon dioxide and water

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51
Q

what is the main enzyme involved in alcohol metabolism

A

alcohol dehydrogenase

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52
Q

what is the reduction in blood alcohol content on average per hour

A

18mg/100ml/hr

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53
Q

what coenzymes needs to be present for alcohol metabolism

A

NAD

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54
Q

what is the toxic metabolite produced in alcohol metabolism

A

acetaldehyde - what causes hangovers

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55
Q

what is acetaldehyde converted to

A

acetate by aldehyde dehydrogenase

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56
Q

what is acetate eventually converted to

A

carbon dioxide and water

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57
Q

what is ADH

A

alcohol dehydrogenase

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58
Q

what are the differences between the different isotypes of ADH

A

different structural, physical and chemical properties
there are fast and slow metabolisers
different Km and Vmax

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59
Q

what is pharmacokinetics

A

how the body metabolises and copes with drugs that are present

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60
Q

what is zero order kinetics

A

cleared at a constant rate regardless of concentration

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61
Q

what order of kinetics is ethanol clearance from the body

A

zero order - cleared at a constant rate regardless of concentration

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62
Q

what does the pharmacokinetics or alcohol depend on

A

liver size and body mass
large liver = more enzymes = more alcohol metabolism
larger body = greater alcohol distribution = less effect

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63
Q

what is the cytochrome p450 pathway

A
  • is an oxidative pathway of alcohol metabolism involving a microsomal enzyme oxidising system (MEOS)
  • the pathway contains a family of enzymes containing heme as a cofactor that function as monooxygenases- catalysis of oxidative reactions
  • the enzymes are predominantly present in the microsomes and contribute to alcohol oxidation in the liver
  • within the system you use up NADPH which affects other pathways
  • the pathway is most prevalent in chronic alcoholics because alcohol concentration is regularly high
  • problem - produces free radical which damage tissue
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64
Q

summarise sections of the road traffic act 1988

A
  • driving a motor vehicle whilst unfit through drink or drugs
  • being in charge of a motor vehicle whilst unfit through drink or drugs
  • driving a motor vehicle after consuming so much alcohol that the proportion in breath, blood or urine exceeds prescribed limits
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65
Q

what are the legal limits of alcohol in Scotland

A

blood - 50mg/100ml
breath - 22ug/100ml
urine - 65mg/100ml

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66
Q

compare Scotland’s legal driving alcohol limits with the rest of the UK

A

they are much lower

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67
Q

what physical samples can we use to measure alcohol content

A 
breath 
urine 
perspiration 
saliva 
blood
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68
Q

what is the best measurement of alcohol concentration and why

A

BAC because it is equivalent to the conc in the brain

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69
Q

what are the 3 most common methods of measuring alcohol content

A

blood - most accurate - rapid equilibration across the blood brain barrier
urine - provides mean value over the period of excretion
breath - in equilibrium with BAC but in very small concs

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70
Q

what are the equations for converting between blood, breath and urine alcohol conc

A

BAC x 1.3 = urine
(mg) (mg)
BAC/2300 = breath
(mg) (ug)

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71
Q

ADH in the presence of its coenzyme, …………….., oxidises alcohol

A

NAD+

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72
Q

how can the reduction of NAD+ during alcohol metabolism be measured

A

calorimetrically

spectrophotometrically

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73
Q

how do electrochemical fuel cell breathalysers work

A

electric current passes through and the conc of alcohol determines the strength of the current

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74
Q

how do IR optical sensor breathalysers work

A

light is fired at a sample and the concentration of alcohol affects the light absorbed

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75
Q

how do dual sensor breathalyser work

A

both chemical and IR

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76
Q

apart from using the 3 types of breathalysers how else can we measure alcohol content of a sample

A

gas chromatography

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77
Q

what is the equation for calculating BAC

A 
Cmax - (t x elimination rate)
where the average elimination rate is 18 
the minimum is 9 and the maximum is 27
t is the number of hours 
Cmax is the maximum alcohol conc
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78
Q

heavy drinkers tend to have increased/decreased rate of alcohol metabolism from the average value

A

increased

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79
Q

why are heavy drinkers faster at metabolising alcohol

A

because they have alcohol dehydrogenase metabolism and the p450 system so they metabolise alcohol more quickly

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80
Q

when given limit and amount of alcohol in sample how do we figure out when the person will be able to drive

A

we find out how much the conc needs to decrease by then divide by the average elimination rate

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81
Q

describe the auto brewery/gut fermentation system

A

if certain yeast are present in the gut at high conc which produces ethanol - would have alcohol in the blood even without having a drink

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82
Q

what is forensic toxicology

A

study of the effect of alcohol, drugs or poisons with application to the law
e.g. post mortem toxicology, human performance, drug testing in the workplace/sports

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83
Q

what is the Paracelsus’s statement about the Paracelsus’s third defence meaning

A

what is there that is not poison, all things are poison and nothing without poison - solely the does determines that a thing is not poison i.e. too much water can cause death

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84
Q

what is the problem with babies being given food that their parents eat

A

there is too much slat in the food and results in kidney failure in the babies

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85
Q

what is a controlled substance

A

any drug subject to misuse under the drugs act 1971

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86
Q

give examples of controlled substances

A

heroin, LSD, solvents - can cause liver kidney and brain damage if used too much, cannabis

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87
Q

what are some reasons for poisoning

A

suicide
accident - too pure, not cut/mixed properly
industrial - poisoning in the workplace
homicide - murder
iatrogenic - murder by healthcare professional

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88
Q

list some Class A drugs

A 
major natural and synthetic opiates 
cocaine 
LSD
injectable amphetamines 
cannabinol 
magic mushrooms 
ecstasy
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89
Q

name some class B drugs

A

oral amphetamines
cannabis plant material and resin
codeine
certain barbiturates

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90
Q

name some class C drugs

A

benzodiazepines
methaqualone
gama hydroxybutyrate
ketamine

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91
Q

what are the 3 drug type categories and give examples of each

A

stimulants - stimulate/activate brain - cocaine
depressants - inhibit brain activity - alcohol, heroin
hallucinogens - induce alterations in perception and mood - LSD, ecstasy

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92
Q

what type of information can we get from drug analysis

A

qualitative/quantitative
bulk/trace
chronic/acute

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93
Q

what are methods of drug analysis

A 
presumptive tests 
TLC 
column chromatography 
HPLC 
gas chromatography and mass spec 
immunoassay 
spectroscopy
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94
Q

what human sample can we use to infer if drugs are from the air or have been inside the body

A

hair

  • drugs bind to melanin - weak bases (bind easily) - the more melanin the better the drug binds - darker haired people have more melanin
  • if the drug has been added to the hair through ingestion or injection there is a pattern but if the drug has been smoked we don’t see a pattern
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95
Q

as well as finding the actual drug in a body sample how else can we finds the drug

A

by looking for it metabolites

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96
Q

which core drugs are tested for in the workplace and what samples do we take to test for them

A 
cannabis
cocaine 
amphetamines
opiates 
testing: saliva, urine, hair
97
Q

what is pharmacokinetics

A

what the body is doing to the drugs

the study of the absorption, distribution, metabolism and excretion processes over time

98
Q

what is pharmacodynamics

A

what the drug is doing to the body

the study of the dose vs. pharmacological response

99
Q

what is pharmacogenetics

A

the study of genetic influences on the absorption, distribution, metabolism and excretion processes - different people react differently to drugs

100
Q

what does ADME stand for

A

absorption, distribution, metabolism and excretion

101
Q

what factors affect toxicity of a drug

A
  • dose response - how much - LD50 value
  • sensitisation - may have an enhanced immune response to a drug the second time
  • tolerance - when repeatedly exposed
  • accumulation - the longer the half life the greater the accumulation
  • bioavailability - proportion of the original does absorbed and the rate at which absorption takes place
102
Q

what is the LD50 value

A

where you get half of the maximum response - it can increase if people build up tolerance

103
Q

what is the general shape of a dose response curve

A

S

104
Q

what drug category are amphetamines in

A

stimulant - they increase dopamine levels

105
Q

how can amphetamines be taken

A

inhalation
injection
ingestion
snorting

106
Q

what are the short term affects of amphetamines

A 
increased wakefulness and physical activity 
decreased appetite 
faster breathing 
rapid/irregular heartbeat 
increased bp and body temp
107
Q

what are the long term affects of amphetamines

A

HIV/AIDS - sharing needles
weight loss
severe dental problems - meth mouth

108
Q

which category of drug is MDMA/ecstasy

A

hallucinogen/stimulant

109
Q

what are the affects of MDMA

A
  • increased activity of dopamine and norepinephrine - increased energy and heart rate/bp
  • affects serotonin levels
  • blurred vision
  • nausea
  • muscle cramping
110
Q

how long do the effects of MDMA last

A

3-6 hours

111
Q

what can high doses of MDMA affect

A

temp regulation

112
Q

what medical profession is MDMA used in but why is it not used very often

A

psychotherapy but not used often due to all the side effects

113
Q

how is cocaine made or extracted

A

by extraction from cocoa leaf

or by chemical synthesis

114
Q

how can you take cocaine

A

snorting, injection, oral

115
Q

what drug category does cocaine belong to

A

stimulant - increases the level of dopamine

116
Q

what are the short term effects of cocaine

A 
extreme happiness and energy 
mental alertness 
hypersensitivity to sight, sound and touch 
irritability 
paranoia
117
Q

what are other affects of cocaine

A 
constricted blood vessels
dilated pupils 
nausea 
raised body temp, bp and heartbeat 
tremors and muscle twitches 
restlessness
118
Q

what are the active ingredients of heroin

A

diamorphines and other opiates e.g. codeine

119
Q

how is heroin administered

A

smoking or IV

120
Q

what are the effects of heroin

A 
analgesia 
dreamy euphoria 
sedation 
respiratory depression - can lead to death
nausea 
vomiting 
cough suppression 
constipation
121
Q

what is respiratory depression

A

when ventilation becomes inadequate for gas exchange causing increased conc of CO2 and respiratory acidosis

122
Q

what category of drug is LSD and what is it made form

A

hallucinogen

made from lysergic acid

123
Q

what are the affects of LSD

A 
affects the action of glutamate and serotonin 
rapid emotional swings
distortion of reality, rationality and communication 
raised blood pressure, heart rate;, body temp
dizziness and insomnia 
loss of appetite 
dry mouth 
sweating 
numbness 
weakness 
tremors 
dilated pupils
124
Q

how is LSD administered

A

microdots

125
Q

how is cannabis administered

A

smoking, dabbing, food

126
Q

how does the class of cannabis change

A 
cannabis plant and resin - class B
cannabis oil - Class A
127
Q

what are the effects of cannabis

A 
euphoria 
nausea 
hypotension 
bloodshot eyes 
poor coordination 
distortion 
munchies
128
Q

how quickly does cannabis act

A

smoking - minutes

oral - 1 hour

129
Q

is cannabis accepted for medical use in the UK

A

no - we are unsure of long term medical use effects

130
Q

what are benzodiazepines

A

prescription drugs

131
Q

how are benzodiazepines administered

A

oral, injection

132
Q

what are the effects of benzodiazepines

A

depressants - reduce tension and anxiety

cause drowsiness

133
Q

what is the date rape drug

A

flunitrazepam

134
Q

what is blood grouping

A

a preliminary screen which defines a persons blood group in a quick and cheap manner allowing elimination of suspects from large samples

135
Q

what are the antibodies on cells and the antigens in serum for each of the different blood types

A 
type - antigen - antibodies
A - A - Anti B
B - B anti A
AB - AB - neither anti A or anti B
O - neither A or B - both anti A and anti B
136
Q

what are the possible allele combinations for each of the blood types and their % distribution

A

O - O - 45%
A - AA, AO - 40%
B - BB, BO - 10%
AB - AB - 5%

137
Q

what is a biological marker

A

a measurable indicator of some biological state or condition

138
Q

we can carry out immunological procedures using ………….. to find our which antigens are present in sample

A

antibodies

139
Q

what are secretors

A

they secrete ABH antigens of ABO blood group in other bodily fluids (saliva, semen, gastric juice etc)
other fluids have a very similar profile to the blood serum

140
Q

secretors have a higher concentration of which antigens

A

A and B

141
Q

what is the difference between secretors and non secretors

A

for secretors we can use other fluids to determine blood type but for non-secretors we have to use blood

142
Q

what case was DNA profilin fist used for

A

Colin pitchfork

143
Q

what are good sources of DNA in the body

A 
wbc 
sperm cells 
hair with follicle 
vaginal fluid 
bones 
teeth
144
Q

what are bad sources of DNA in the body

A

skin cells - better with new technology
urine
hair shaft - only mDNA
faeces

145
Q

what is the same in identical twins

A

DNA and micro RNA expression

146
Q

what are some marker types for autosomes

A

STRs
SNPs
SNPs don’t have the best discriminatory power so we are best to use STR

147
Q

what are the markers for mitochondrial DNA

A

SNPs

148
Q

what is RFLP

A

restriction fragment length polymorphism

  • cuts up DNA using restriction enzymes
  • there are STRs within the cut up sections and the lengths of repeats very among individuals
  • a DNA sample is digested into fragments by one or more restriction enzymes and the resulting fragments are separated by gel electrophoresis
149
Q

what are the limitations of RFLP

A

large amounts of DNA are required

requires undegraded material

150
Q

what is the method of using PCR to amplify STRs

A

we use PCR then gel electrophoresis

151
Q

why are STRs good for forensics

A

because the number of repeats of STR markers can be highly variable among individuals

152
Q

why is a smaller STR better

A

PCR amplification of degraded DNA works better with smaller target product sites
because of the smaller size STR alleles they can also be separated form other chromosomal locations ensuring closely linked loci are not chosen

153
Q

what are the benefits of PCR of STRs

A

STRs have lower mutation rates making them more stable and predictable
STRs with higher power of discrimination can be chosen for forensics
less DNA is required
we can use partially degraded material

154
Q

what is used more often PCR or RFLP

A

PCR

155
Q

how is PCR of STRs now automated

A

samples are tagged with fluorescence and put through a capillary gel which gives readings based on fluorescent tags

156
Q

what is the difference between STRs and SNPs in terms of fluorescence tagging

A

SNPs are tagged with fluorescence bases

157
Q

how many circular molecules of DNA does 1 mitochondria have

A

5-10 each with 37 genes

158
Q

when is mtDNA useful in forensics

A

in mass disasters to link family members as it is passed from mother to children
discrimination is limited especially if individuals are maternally related
still effective when:
very small sample
badly degraded

159
Q

describe Y chromosome testing

A

it uses amelogenin locus and/or STRs on the y chromosome
- amelogenin codes for enamel in teeth and in the X chromosome if 6bp shorter
- in testing, 2 peaks represents a males as there ar 2 different lengths of DNA present
- STRs on the y chromosome only appear in male samples and can be seen of autosomal and y chromosome profiles
useful for mixed gender samples - sexual assault
but low discriminatory power

160
Q

what is the main DNA analysis and why

A

autosomal STR due to the high discriminatory power

161
Q

when is autosomal SNNP analysis used

A

when sample size is too small for autosomal STRs

162
Q

what is low copy number analysis

A

used when we have little DNA

163
Q

what is familial searching

A

it is based on the principle that relatives will share features of their DNA profiles more than unrelated individuals

164
Q

what is heteroplasmy

A

the presence of more than one type of DNA within an organisms
low level variation

165
Q

mitochondrial DNA has a high/low mutation rate

A

low - it changes very little when passed maternally through families

166
Q

what is DNA boost

A

computer programme which searches DNA profiles

the database creates all possible genotypes of a mixture with different STR length repeats

167
Q

what are some applications of DNA profiling

A 
familial searching 
cold cases - look at cases that were closed before DNA profiling was available 
linking/identifying families 
wildlife crime 
ethical issue
168
Q

what is codis

A

US based system that uses 13 core STR loci

169
Q

what is UK NDNAD

A

the system uses 11 loci in total including 10 STR loci and XY (amelogenin)

170
Q

how do we calculate the probability of finding a DNA match on DNA database systems

A

number of times the event happened/ the number of times the event could have happened

171
Q

what are the 3 possible categories of results when carrying out DNA profile comparisons

A

exclusion - non-match
inclusion - match
inconclusive

172
Q

how do we work out probability for 2 allele locus

A

F(1, 1) = p^2

F(1, 2) = 2pq

173
Q

what are the 2 possible errors that can occur in PCR STR amplification

A

backwards slippage

forward slippage

174
Q

what is backward slippage

A

causes an insertion - an extra STR repeat is inserted

175
Q

what is forward slippage

A

causes a deletion - an STR repeat is lost - very small bands (stutter products are produced due to this mechanism

176
Q

what are the advantages and disadvantages of low copy number analysis

A

only need small amounts of DNA template
it has the same discriminatory power as routine DNA profiling
the process takes longer because a greater number of PCR cycles are required to get sufficient DNA quantities

177
Q

what is a partial DNA profile and what can they be used for

A

they are DNA profiles that are not complete - this may be due to low quality DNA possibly due to degradation of the sample or insufficient quantity
they can be used for familial searching
we can look for similarities in the profile that are on the database
we can use low copy number analysis

178
Q

how do we increase the probability of finding a match with a partial profile

A

we have to prioritise using specific parameters for example location and police intelligence

179
Q

give an overview of the M3 murder

A

a group of men tried to steal a car and threw bricks from a bridge on the M3
the mixed profile from the brick matched that in the car by using low copy number DNA but they found no match on the database
familial search was carried out they found the suspect

180
Q

what programme in particular has become very useful for cold cases

A

DNA boost

181
Q

what was operation magnum

A

the first use of familial searching on NDNAD
several women were murdered and low copy number analysis found matches on their clothes
a familial search was carried out and the suspect was found

182
Q

outline the shoe rapist incident

A

women were being raped by a man that was keeping their shoes
familial search used lead them to the sister of the rapist and they found him

183
Q

outline the Romanovs case

A

tsar, wife and 5 kids executed
a grave was found and STR and mtDNA analysis found that 5 of the 9 skeletons were related
woman claimed to be Anastasia by had different mtDNA

184
Q

what markers can we use for visual identification

A

hair, skin colour, eye colour, piercings, tattoos

185
Q

in bosnia there are ~40 burial sites and blood and bone samples were taken and compared with relatives - what were the difficulties with this

A

whole families were killed - nothing to compare with

shallow graves - bodies dug up by animals and bones scattered

186
Q

give an example of a mass disaster and false identification

A

tsunami in indian ocean - people were so distraught that they were wrongly identifying bodies as family members

187
Q

what did the 9/11 disaster lead to

A

new extraction methods from bone
mini STRs - shorter area - easier analysis
use of SNPs
use of mtDNA

188
Q

sadaam Hussein had body doubles, how did they identify him

A

by use of Y STR haplotypes

189
Q

what is genetic diversity caused by

A

polymorphisms

190
Q

how can we detect genetic diseases by RFLP and PCR

A

mutations can cause changes in the restriction sites and the size of fragments

191
Q

give examples of genetic diseases that can be detected by RFLP or PCR

A

sickle cell anaemia

cystic fibrosis

192
Q

give some examples of wildlife crime

A

crime towards rare animals can cause threat to species
we can trace crimes by looking at non human DNA profiles
animals can be victims of crime but animals can also cause damage to humans e.g. traffic accidents and flesh and bone damage

193
Q

what is entomology

A

the study of insects

194
Q

what are the areas of application of entomology in forensics

A

we use insects to infer the cause, time and details of death

  • some insects inhabit remains
  • some insects cause damage to structure
  • some insects infest foods
195
Q

what are some of the forensic associations of insects

A

found on corpses e.g. diptera
food spoilage e.g. butterflies
structural damage e.g. beetles
illegal trade in protected species e.g. butterflies
indication of neglect e.g. lice and fleas
cause of death e.g. wasps

196
Q

why do lice leave the body when it dies

A

because they need the warmth

197
Q

what is the post mortem interval

A

the interval between the time of death and the post-mortem exam and is often given as an estimate in a range

198
Q

what methods can be used to determine PMI

A 
Algor mortis 
livor mortis
rigor mortis 
changes in eye fluid 
stomach and bone contents 
decomposition changes 
insect colonisation 
circumstantial evidence
199
Q

what is Algor mortis

A

cooling of the body

200
Q

what is livor mortis

A

hypostasis - gravity causes blood to sink

201
Q

what is rigor mortis

A

stiffening of the body

202
Q

how can we infer PMI from stomach and bowel contents

A

we might be able to so what someone has eaten - may lead us to a location
might indicate an allergy
might indicate when food was consumed

203
Q

how can insect colonisation indicate PMI

A

successive colonisation can indicate time of death - what species are present indicates how long the body has been dead for

204
Q

what is circumstantial evidence

A

evidence that requires inference to conclude facts e.g. finger prints at crime scene

205
Q

how does the season affect entomology

A

season of death if one is outside can majorly impact the insects that will colonise and also affects the rate of decay

206
Q

what is meant by insects colonising successively

A

they don’t all arrive at once - they arrive in stages - specific species prefer different levels of decay

207
Q

how can we interpret changes in location after death using entomology

A

the insects found on a corpse may not be local to a particular area so this would indicate that the body was moved after death

208
Q

give examples of how circumstances of death can affect insect colonisation

A
  • was the body on the surface for a while then buried
  • was the body in water if so what kind and in what season- aquatic insects
  • toxicology - some insects eat flesh or blood - these insects can be analysed to check for drugs etc
209
Q

development time of insects is ……………. dependent

A

temperature

210
Q

give 7 reasons why insects are successful

A 
1 - metamorphosis 
2 - feeding strategies 
3 - sophisticated behaviours 
4 - small and difficult to catch 
5 - chitin exoskeletons 
6 - wings - can easily evade danger 
7 - life cycles - intricate and efficient
211
Q

what is metamorphosis and why does it improve success of insects

A

the process by which an animal physical develops after birth which involves changes in the body structure through cell growth and differentiation
metamorphosis is often accompanied by a change in nutrition source or behaviour which allows them to exploit other resources

212
Q

why are feeding strategies of insects a contributor to their success

A

they have very specific feeding strategies

213
Q

give examples of sophisticated behaviours of insect that improve their success

A

many insects use sensory neurons to attract them to other sites

214
Q

why is chitin an advantage to insects

A

it is a hard coating which forms their exoskeleton and acts as part of their defence mechanisms

215
Q

what do the insects do once they have exploited the nutrients from the corpse

A

they leave the corpse

216
Q

how can insects be mistakenly associated with a crime

A

they may be caught in the clothing or be landed on but they are not actually feeding on the body, they are just in close proximity with it

217
Q

how can invertebrates be the cause of death

A

some invertebrates are venomous

some people have allergies to insects

218
Q

what are the 5 stages of entomological succession

A
  1. blowflies
  2. flesh flies
  3. burying/histerid beetle
  4. house flies
  5. dermestid beetles
219
Q

what are the stages of corpse decomposition

A
  1. fresh - body starts cooling - autolysis - hypostasis and rigor mortis may begin
  2. bloat - discoloration, body swelling - fluid expelled form orifices - rapid decay dur to intense microbial and invertebrate activity - soft tissue decay
  3. putrefaction - loss of skin and soft tissue - deflation - decay by microbes and invertebrates slows down once soft tissue is removed and body dries out
  4. putrid dry remains - slow progress of decay - loss of uterus and prostate gland , tendons, cartilage, fingernails and hair - skeleton may become disarticulated what
220
Q

what is an instar

A

an insect stage of development

221
Q

what are the first organisms to arrive at a corpse

A

flies - blowflies, flesh flies, house flies

222
Q

what are the stages of the blowfly life cycle

A
  1. adult female blowflies arrive within minutes to lay eggs on a corpse in wounds and natural openings
  2. in 24 hrs the eggs hatch into 1st stage maggots
  3. with feeding they moult to 2nd stage maggots
  4. with further feeding they moult to 3rd stage maggots
  5. with further feeding the maggots move away from the body to metamorphose and develop into flies
223
Q

what is there an increased threat to used pathogens for

A

to release them maliciously or to cause distress

224
Q

what environmental conditions can affect decomposition

A

cold, dry - slow decomp

warm, moist - fast decomp

225
Q

are we able to work out the time of death by looking at microbes

A

not yet

226
Q

how can microbes be used as identification tools

A

soil microbes - where has the body been
saliva microbes - what have we been eating
microbial infection
food poisoning - trying to find the source

227
Q

what are the 6 types of evidence covered in this course that are collected from forensic examination

A
  • time of death - can help look at alibies
  • trace evidence - hair, fibres etc
  • blood patterns - different types - can indicate trauma type
  • DNA profiling - can connect evidence to suspects
  • Entomology - insects and forensic use
  • toxicology - drugs
228
Q

what is a nomogram

A

we measure rectal temperature and ambient temperature and plot lines

  • where the lines cross we draw a line through the central point and the crossing point
  • we know the weight so we follow around the curve to get the estimated time of death
229
Q

how can we calculate the number of hours since death using body temperature

A

98.4 - internal body temp/ 1.5

230
Q

what are the indications of time of death form stiffness and warmth

A

warm not stiff <3hrs
warm stiff 3-8 hrs
cold stiff 8-36 hours
cold not stiff >36 hours

231
Q

are insects more accurate for inferring longer or shorter times after death

A

longer

232
Q

what factors can enhance the cooling of a body

A 
small body
low fat 
stretched out 
body dismembered
serious blood loss
no clothes 
wet clothes 
strong air currents 
low ambient temp 
body in cold water
233
Q

what factors delay body cooling

A 
large body 
high fat 
foetal position 
clothing 
insulative covering 
protection from draught 
warm ambient temp 
microclimate warm 
exposed to sun 
high humidity
234
Q

what is pressure pallor

A

white mark where the pressure was on the corpse

235
Q

outline the soham murders

A

hairs and fibres found on girls football shirts in bin and the evidence was linked back to the suspect due to finding the same fibres in his house

236
Q

outline the jill dando case

A

BBC presenter shot at her door - polyester fibres and gun residue on her coat led investigators to the suspect

237
Q

why are some clothing items not very discriminatory

A

if they are popular then they are not very discriminatory

238
Q

outline the billie jo Jenkins case

A

they found an impact scatter at the scene and thought it was caused by trauma initially but it was actually caused by pulmonary emphysema - much debate between experts - required a lot of collaboration

239
Q

describe the Harold shipman case

A

possibly committed 200 murders but will never be certain unless all bodies are exhumed and re-examined
he was found out through false entries - false signature
found high morphine content in victims bodies

KSB (5 decks)

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