Case Assessment and Interpretation Flashcards

1
Q

what is expected from forensic scientists from the court and police (2)

A

intelligence on topics people do not know about

providing evidence and timely scientific support

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is expected of forensic scientists from the politicians and rest of society (3)

A

rapid results which are not always achievable
an objective opinion
crime reduction and prevention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is CAI

A

a logical detailed assessment of what you are doing before you open the evidence bag

consider what you have been asked to do and what is needed for the case

not done in all countries but done in UK

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

why was CAI brought about

A

in the 1998

the forensic science service had a large backlog and long turnaround times

drowning in unnecessary analysis times and struggling to meet deadlines

failing to meet needs of court and police

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the purpose of CAI (7)

A
  1. improve the use of resources
  2. improve decision making process
  3. prevent wasting time
  4. service the needs of the justice system
  5. need for the people asking to be more specific (eliminate term forensicate)
  6. improve relationships between police and scientists
  7. give value
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

why is preventing wasting time important

A

for case turnaround as the demand can be high for scientists

things that take longer = higher cost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what could be correlated to people not submitting evidence because of the cost that comes with it

A

miscarriages of justice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what two things must be set in CAI

A

your propositions

prosecution and defence ones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

when is a proxy proposition necessary

what is this also called

A

when the offender gives a no comment so we are unaware of the defence being put forward

could also be called the alternative proposition - in the absence of this it is impossible to evaluate your findings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

give two common defence strategies

A

self defence
contamination during evidence collection or analysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

is case context necessary in CAI

A

yes, in order to set your propositions and set your examination strategy by considering what is needed for the case

be careful of bias though - even if it is subconscious

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the forensic strategy

what 7 things does it involve

A

a systematic approach to gathering and analysing evidence to make interpretations that can be presented in court

involves:
evidence identification
preservation
examination + analysis
documentation
interpretation
reporting
expert testimony

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what does CAI enhance in the evidence you present

A

THE VALUE OF IT

value is not the lowest cost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what document provides information of CAI for experts in forensic science

A

the best practice manual for crime scene investigation from ENFSI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

give two things to be considered when you are setting you examination strategy

A

probative value of methods

destructive techniques

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is there a need for in your CAI

A

good communication of the expected outcomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are the two elements of CAI

A

assessment = how you are going to manage your evidence, what analyses you are going to prioritise

interpretation = how are you going to report the findings in a logical, quantitative and accessible way to aid the understanding of what you have done to others

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are the three stages in CAI

A
  1. customer requirement, need and case info
  2. pre-assessment, determine forensic strategy and make propositions
  3. examination, evaluate outcome, interpret and report
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what should you do if a customer directs you to an examination strategy you feel is inappropriate

A

advise them why and suggest how else it should be done with their aims still present

discuss the limitations with them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are the aims and benefits of case pre assessment (5)

A
  1. can consider potential findings beforehand
  2. set out most appropriate examination strategy
  3. find hypotheses
  4. set the findings you will prioritise
  5. assign probabilities to the LR and then these can be refined when the evidence has been analysed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what statement is good to include at the beginning of your report

A

if further evidence or info comes to light it may be necessary for me to reconsider my conclusions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

in the assessment of evidence, what are the hierarchy of propositions

A

sub source
source
activity
offence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

give an example of a sub source proposition

A

two DNA profiles matching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
give an example of a source proposition
the blood on X's clothing came from Y the glass fragment came from window X
26
give an example of an activity proposition
Mr A was present when the window was smashed Mr has sexual intercourse with Mrs
27
give an example of an offence proposition
Mr A committed the burglary Mr assaulted Mr
28
what type of propositions can expert witnesses generally only give
source or sub source
29
how much evidence does an activity level proposition generally need
more than 1
30
why cant we give activity level propositions
due to evidence transfer and we weren't actually there so it would be hearsay
31
who determines offence level propositions
the court/jury
32
give 5 things CAI requires to be effective
1. good communication between parties 2. an understanding of the requirements 3. agreement on a forensic strategy 4. understand the expected outcomes 5. explore the staged approach when needed
33
what are the three stages in the forensic process
investigation evaluation adjudication (court)
34
does everything from crime scene examination reach the court
no it is not always needed
35
what is the staged approach in forensic science what three things does this ensure
a part of CAI = a systematic process used by investigators to examine and analyse evidence used as a flow chart ensures the thoroughness, accuracy and reliability
36
what are the 8 stages in the staged approach
1. incident or arrest 2. recognition - identify potential evidence 3. documentation - contemporaneous notes, sketch, photos 4. collection - use of tools and techniques avoiding evidence contamination and damage 5. preservation - package, label, store 6. analysis - scientific methods 7. interpretation - draw conclusions based on scientific findings 8. reconstruction - of events based on evidence
37
how does the staged approach help forensic scientists (7)
1. ensure we have clear understanding of case and issues 2. defines propositions for testing 3. adds value to scientists role 4. agreed forensic strategy 5. prevents time and money wasting 6. prevents overloading of samples 7. ensure everyone is doing the same process
38
what is Bayesian reasoning in forensic science
applying Bayesian probability theory to evaluate and interpret forensic evidence within the context of a criminal investigation for legal purposes
39
what are the key elements involved in Bayesian Reasoning in forensic science (5)
1. prior odds 2. likelihood ratio 3. Bayes theorem 4. posterior odds 5. making informed decisions
40
what does Bayesian reasoning help us do in forensic science (3)
quantify and integrate the strength of evidence into the overall case assessing the significance of our findings by enhancing objectivity and reliability of expert testimony in court make informed decisions
41
what is bayes theorem
a statistical principle used to assess the probability of a hypothesis quantifying how strongly evidence supports or rejects a hypothesis
42
what are the two categories in Bayes Theorem
logic = addressing probability of evidence given the hypothesis and the background information balance = address the two propositions and if only one can be addresses state why and give a proxy proposition
43
what must be stated about the propositions you put forward
they are subject to change based on new info or when you actually start analysing the evidence
44
what are the 4 pieces that make up bayes theorem combined what do these provide
I = case/background information E = scientific evidence Hp = prosecution hypothesis Hd = defence hypothesis or alternative proposition the likelihood ratio
45
What is the likelihood ratio and what is it used for
a statistical measure of quantifying the strength of evidence weighs the two propositions against each other and see which is supported more strongly the probability of the evidence given the prosecution hypothesis and information divided by the defence hypothesis and information
46
what kind of probabilities does the likelihood ratio use
conditional probabilities
47
what are the prior odds
the odds of a hypothesis before any new evidence has been taken into account your initial belief on the likelihood of the hypothesis being true or false
48
what are the posterior odds
the updated odds of the hypothesis after the evidence has been examined calculated by doing prior odds x likelihood ratio
49
what happens if only one proposition can be given by the scientist
it is fine for the expert can only address one proposition but this should be made clear and the fact they cannot evaluate the strength of the evidence
50
what is transposing the conditional should it be done what is this a synonym for give an example of a case where this was seen
the probability of the proposition (the accused being guilty) given the evidence no the prosecutors fallacy R vs Doheny
51
give an example of a statement that represents transposing the conditional
normal = assuming our subject is a basketball player would be fair to conclude he is tall transposing the conditional = assuming they are tall assumes they are a basket ball player
52
what happened in the R vs Doheny Case
considering DNA profile matches expert witness was misled to answering a question and he gave his opinion that the accused left the stain at the scene he transposed the conditional due to the questions he was being asked on the stand
53
what is the base rate and how is this calculated
this is the prior odds of an event occurring in the absence of background info or evidence represents the general occurrence of something in everyday life of a given population calculated = the probability of the event e.g the probability of a certain crime happening the a city BASED ON CONDITIONAL PROBABILITIES
54
what does a likelihood ratio of more than 1 support
supports prosecution hypothesis
55
what does a likelihood ratio of 0 support
neutral - supports neither hypothesis
56
what does a likelihood ratio of less than 1 support
supports defence hypothesis
57
how do we get the values used in calculating likelihood ratios
use estimated values based on past cases from the experts professional experience or using databases e.g the laboratory management system
58
what likelihood ratio value extremely strongly supports the hypothesis
more than 1 million
59
what likelihood ratio value very strongly supports the hypothesis
10,000 - 1 million
60
what likelihood ratio value strongly supports the hypothesis
1,000 - 10,000
61
what likelihood ratio value moderately strongly supports the hypothesis
100 - 1,000
62
what likelihood ratio value moderately supports the hypothesis
10 - 100
63
what likelihood ratio value weakly supports the hypothesis
1 - 10
64
what is there no need to examine all evidence that has been submitted (3)
reduce cost and turnaround time too much info can confuse people take the staged approach and only use what is needed
65
what are potential evidence types you many come across in the assessment part of CAI how will these affect the order you analyse things
blood urine DNA fibres hairs paints think what is likely to persist longer and examine that last
66
what two things do you need to consider when deciding the order of analysing different evidence types
transfer and persistance transfers can be direct or indirect
67
what things affect the transfer of evidence (7)
pressure number of contacts how easily it transfers liquid or solid how much is involved in the contact substrates transferred to and from weather conditions - how evidence will persist (degradation)
68
what are the expectations of the expert in the interpretation of evidence they have analysed (8)
explain to the non expert clear and concise good communication good scientific methods don't use misleading statements like might have or could have explore all reasons for the outcomes you found use of propositions and likelihood ratio clear methods and examination strategy
69
what is an example of a case that shows as an expert you need to consider other possible reasons for the outcomes you found
the Birmingham Six