“Source” or “Activity” What is the Level of Issue in a Criminal Trial?

Jackson, G.; Biedermann, Alex

doi:10.1111/j.1740-9713.2019.01253.x

Cited by 7 publications

(4 citation statements)

References 2 publications

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“…One might be tempted to say, yes, this is possible. However, as stated in [ 65 ] “if at the end of the expert’s evidence, the fact-finder is left with, on the one hand, an impressive big number (the LR given sub-source propositions) and on the other hand, a list of possible explanations for the transfer (as a result of specific activities), how do they decide what the DNA evidence means, and how does the evidence impact their decision?”.…”

Section: Communication Reporting and Testimonymentioning

confidence: 99%

A Logical Framework for Forensic DNA Interpretation

Hicks

Buckleton

Castella

et al. 2022

Genes

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The forensic community has devoted much effort over the last decades to the development of a logical framework for forensic interpretation, which is essential for the safe administration of justice. We review the research and guidelines that have been published and provide examples of how to implement them in casework. After a discussion on uncertainty in the criminal trial and the roles that the DNA scientist may take, we present the principles of interpretation for evaluative reporting. We show how their application helps to avoid a common fallacy and present strategies that DNA scientists can apply so that they do not transpose the conditional. We then discuss the hierarchy of propositions and explain why it is considered a fundamental concept for the evaluation of biological results and the differences between assessing results given propositions that are at the source level or the activity level. We show the importance of pre-assessment, especially when the questions relate to the alleged activities, and when transfer and persistence need to be considered by the scientists to guide the court. We conclude with a discussion on statement writing and testimony. This provides guidance on how DNA scientists can report in a balanced, transparent, and logical way.

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Section: Communication Reporting and Testimonymentioning

confidence: 99%

A Logical Framework for Forensic DNA Interpretation

Hicks

Buckleton

Castella

et al. 2022

Genes

Self Cite

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“…Listing the possible explanations for the presence of DNA is more suited to our role as investigators -which takes place during the period prior to a defendant being put forward for prosecution. As outlined by Jackson and Biedermann [30], if the jury is told that the DNA results are a billion times more likely if the DNA comes from the suspect rather than from some unknown person, and that they are then given a list of explanations, it will be difficult for them to decide what the DNA evidence means and how it impacts the case. They will be left with a huge number that might have no bearing on the case (i.e., the source of the DNA may not be contested), and with no value for the results that do have an impact (i.e., results support one proposition, the alternative or none).…”

Section: Context: Our Role As Evaluators Assessing Results Given Propositionsmentioning

confidence: 99%

DNA commission of the International society for forensic genetics: Assessing the value of forensic biological evidence - Guidelines highlighting the importance of propositions. Part II: Evaluation of biological traces considering activity level propositions

Gill

Hicks

Butler

et al. 2020

Forensic Science International: Genetics

108

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The value of the evidence depends critically on propositions. In the second of two papers intended to provide advice to the community on difficult aspects of evaluation and the formulation of propositions, we focus primarily on activity level propositions. This helps the court address the question of "How did an individual's cell material get there?". In order to do this, we expand the framework outlined in the first companion paper. First, it is important not to conflate results and propositions. Statements given activity level propositions aim to help address issues of indirect vs direct transfer, and the time of the activity, but it is important to avoid use of the word 'transfer' in propositions. This is because propositions are assessed by the Court, but DNA transfer is a factor that scientists need to take into account for the interpretation of their results. Suitable activity level propositions are ideally set before knowledge of the results and address issues like: X stabbed Y vs. an unknown person stabbed Y but X met Y the day before. The scientist assigns the probability of the evidence, if each of the alternate propositions is true, to derive a likelihood ratio. To do this, the scientist asks: a) "what are the expectations if each of the propositions is true?" b) "What data are available to assist in the evaluation of the results given the propositions?" When presenting evidence, scientists work within the hierarchy of propositions framework. The value of evidence calculated for a DNA profile cannot be carried over to higher levels in the hierarchy -the calculations given sub-source, source and activity level propositions are all separate. A number of examples are provided to illustrate the principles espoused, and the criteria that such assessments should meet. Ideally in order to assign probabilities, the analyst should have/collect data that are relevant to the case in

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“…The debate then centers around the question 'how did his/her DNA get there'? Forensic scientists approach such questions by performing activity-level evaluations [1][2][3][4][5][6][7][8]. Figure 1 shows activity-level evaluation in the context of forensic human biology analyses.…”

Section: Prosecution and Defense Scenariomentioning

confidence: 99%

On the Identification of Body Fluids and Tissues: A Crucial Link in the Investigation and Solution of Crime

Sijen

Harbison

2021

Genes

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Body fluid and body tissue identification are important in forensic science as they can provide key evidence in a criminal investigation and may assist the court in reaching conclusions. Establishing a link between identifying the fluid or tissue and the DNA profile adds further weight to this evidence. Many forensic laboratories retain techniques for the identification of biological fluids that have been widely used for some time. More recently, many different biomarkers and technologies have been proposed for identification of body fluids and tissues of forensic relevance some of which are now used in forensic casework. Here, we summarize the role of body fluid/ tissue identification in the evaluation of forensic evidence, describe how such evidence is detected at the crime scene and in the laboratory, elaborate different technologies available to do this, and reflect real life experiences. We explain how, by including this information, crucial links can be made to aid in the investigation and solution of crime.

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“Source” or “Activity” What is the Level of Issue in a Criminal Trial?

Cited by 7 publications

References 2 publications

A Logical Framework for Forensic DNA Interpretation

A Logical Framework for Forensic DNA Interpretation

DNA commission of the International society for forensic genetics: Assessing the value of forensic biological evidence - Guidelines highlighting the importance of propositions. Part II: Evaluation of biological traces considering activity level propositions

On the Identification of Body Fluids and Tissues: A Crucial Link in the Investigation and Solution of Crime

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