ENFSI Flashcards
What is an evaluative report?
is any forensic report containing an evaluative reporting second
it provides:
* an assessment of the strength to be attached to the findings
* in the context of alleged circumstances
What are the types of reporting?
- Evaluative
- intelligence
- investigative
- technical
What do forensic practitioners do?
- report only on matters within their area of expertise
- give conclusions that require specialist knowledge
What are the two conditions that must be met for an evaluative report to be produced for court?
- the forensic practitioner has been asked by a mandating authority or party to examine and/or compare material
- the forensic practitioner seeks to evaluate findings with respect to particular competing propositions set by the specific case circumstances or as indicated by the mandating authority
What is the measure of uncertainty based upon?
- the findings
- associated data
- expert knowledge
- case specific propositions
- conditioning information
What does the likelihood ratio measure?
the strength of support the findings provide to discriminate between propositions of interest
What will the key issues in the case be established by?
- considering all available, relevant information
- where necessary, requesting additional information
- agreeing by discussing
What are the pre-assessment aims?
- consider potential findings before examination
- identify most appropriate examination strategy
- specify main potential findings from scientific examinations of the items submitted
- assign probabilities for potential findings regarding each proposition
What are the four requirements for reporting?
- balance
- logic
- robustness
- transparency
What does the ‘balance’ requirement for reporting mean?
- the findings should be evaluated given at least one pair of propositions
- usually one based on one partys account and one on the alternative
- if no alternative can be found: the value of the findings cannot be assessed
What does the ‘logic’ requirement for reporting mean?
Evaluative reports should address:
1. the probability of the findings
2. given the propositions
3. and relevant background information
What does the ‘robustness’ requirement for reporting mean?
the reporting should be capable of sustaining scrutiny and cross-examinating and based upon:
* sound knowledge
* experence
* use of data
What does the ‘transparency’ requirement for reporting mean?
- should be written so that it is suitable for a wide range of readers
- may include supplements explaining technical background
- report conclusions should be derived from a demonstrable process in both case file and report
What propositons will an evaluative statement relate to?
- sub source
- source
- activity level
What conditions affect transfer amount?
- pressure applied during contact
- number of contacts
- how easily the item transfers
- form of the evidence
- how much of the item is involved in the contact
What is indirect transfer?
involves one or more intermediate objects
* complicated
* potentially misleading
* cannot tell the difference between secondary and tertiary (most of the time)
What is persistence?
second part of the transfer process
* could further transfer
* degrade
What influences how long evidence persists?
- what the evidence is
- the location of the evidence
- the environment around the evidence
- time from transfer to collection
- activity of or around the evidence location
What case shows the impact of persistance?
Suffolk murders 2006
* dna evidence
* fibers
* hairs
* footprint and tire impressions
What do you do if there is an absence of an alternative proposition?
- adopt alternative propositions that are most likely
- explore a range of explanations
- state the findings in a technical report, stressing that in the absence of an alternative proposition it is impossible to evaluate the findings
What should you do if there is an absence of specified propositions?
Provide:
1. intelligence report
2. investigative report
3. technical report
no evaluative report
What was the case of R v Weller 2010?
- accused of penetrating a woman
- convicted by DNA evidence under fingernails
- however there were many situations where he could have got her DNA under his fingernails without penetrating her - but the situations that were given would have given low DNA transfer
If no likelihood ratio can be assigned what does this mean?
no appropriate evaluative assessment of the findings can be made
What are the two forms of evidence/reporting?
Categorical and evaluative
What are examples of categorical evidence?
- fingerprints
- drug test data
What are some examples of evaluative evidence?
- DNA
- fibres
What are the two things that are balanced between to make an evaluation of the strength of the findings?
- degree of correspondence between features shared by the two specimens
- probability that those features would be observed in another source
this assigns a likelihood ratio
What is mandating authority?
who commissions the work (police)
Gives some examples that should be included in a case file
8 points
- case info
- materials and items received
- key issues and propositions of interest
- methods used
- examination strategy
- potential outcomes and assigned probabilities
- observations made and analytical results
- conclusions and report
What should be included in a report?
9 points
- conditioning info used
- mandate and questions asked
- propositions of interest
- relevant items collected/received
- items examined
- significant findings
- discussion and evaluation
- conclusion
- a caveat that any change in conditioning info may require assessments, conclusions and/or proposistions be reviewed
International standard to specify gneral requirments for?
testing and calibration
Unonditional probability also referred to as?
Marginal
What is the type of probability where one event is dependent upon another?
conditional
What ensures that professionals know the latest techniques, tools and best practices?
continuing professional development
UKAS ensures that forensic science labs adhere to these to promote consistency?
standardisation
What were the four points of contact in the case of R v Weller?
- victims hair
- touching victim to put her to bed
- contact with vomit
- inserting fingers into vagina
What should the conclusions be like in a report?
- expressed either by a value of the likelihood ratio and/or using a verbal scale related to the value of the likelihood ratio
- the verbal equivalents shall express a degree of support for one of the propositions relative to the alternative
- choice of the reported verbal equivalent is based on the likelihood ratio and not the reverse
- contain an indication of the order of magnitude of the likelihood ratio
What does the regulator say?
- different disciplins have evolved their own ways of assessing that probative value
- current guidance sets out a scientific approach to evaluating observations
- aims to reduce variability and increase transparency - adopt common terminology
Name 10 disciplines that the codes apply to
- blood pattern analysis
- collision investigation
- digital forensics
- DNA and body fluid examination + analysis
- fingerprint comparision
- fire investigation
- firearms examination
- toxicology
- vehicle examination
- trace evidence examination + analysis
What is the framework for case management?
- reviewing the nature of the expert evidence being requested
- establishing the key issues to be addressed
- determining what examinations & analyses are required
- commissioning those examinations & analyses
- interpreting the observations
- writing a report
- appearing in court
Which case shows the importance of understanding DNA transfer?
Lukis Anderson
* His DNA was found under the victims fingernails but he didnt commit the crime
How do experts get the figures for likelihood ratios?
- relevant and appropriate published data
- unpublished sources may be used if no published data is available
- personal data - experience in similar cases and peer consultations (must be justified)
R v William Francis Jones
- his DNA was found on a firing pin of a grenade
- he gave a no comment interview
- couldnt distinguish between direct or indirect transfer - no conclusioned reached re the likelihood
- while direct was more probable it was not sufficient for the finding of guilt
