Activity level DNA evidence evaluation: On propositions addressing the actor or the activity

Area of Science:

• Forensic Science
• Probabilistic Genotyping
• Evidence Evaluation

Background:

• Disputes in forensic DNA analysis often concern the activity or timing of DNA transfer, not its source.
• Legal practitioners increasingly require quantitative evaluations of DNA evidence based on competing propositions.

Purpose of the Study:

• To explore how different defense propositions influence the evaluation of DNA evidence.
• To demonstrate the application of Bayesian networks in assessing DNA evidence under various scenarios.

Main Methods:

• Formulating propositions based on defense claims: crime denial, unknown/known perpetrator, or legitimate activity.
• Utilizing Bayesian networks to model and analyze the impact of these propositions on DNA evidence evaluation.

Main Results:

• The formulation of propositions significantly affects the evidential value assigned to DNA traces.
• Bayesian network analysis provides a structured framework for understanding these effects.

Conclusions:

• The way propositions are framed is critical for accurate DNA evidence interpretation in legal contexts.
• A systematic approach using probabilistic methods can aid in resolving disputes over DNA transfer events.