University Presentation Showcase: Undergraduate Division

Project Title

Modeling Assault From Touch DNA

Presenter Hometown

Richmond

Major

Forensic Science

Department

Chemistry

Degree

Undergraduate

Mentor

Dr. Jamie Fredericks

Mentor Department

Chemistry

Abstract

Touch DNA is biological material left behind when an individual has handled an object. Forensic medical examiners are often required to collect biological material from individuals that claim to have been assaulted and is playing an increasing role in solving crimes. This aim of this study was to determine whether the forces applied during a mimicked aggravated assault scenario could be modeled from the DNA collected. Using novel equipment, we investigated the nature of touch DNA transfer, including DNA concentration and subsequent profile generated, when different measures of force are applied and multiple ‘assailants’ made skin to skin contact with a 'victim'. We wanted to determine whether primary and secondary DNA transfer could aid investigators in determining the sequence of events.

Preliminary results have shown that although there was no correlation between the concentration of DNA collected and the average force applied, or the contact time of single strikes, it was possible to determine the sequence of participation when two participants strike the skin pad (one after each other). In 89 % of the samples, the second individual that punched the skin pad was observed to be the major contributor.

This study demonstrates that touch DNA has the potential to determine the sequence of punches when a victim is subjected to multiple strikes by multiple individuals. This information can play a pivotal role in collaborating eyewitness statements and establishing the ‘by who and when’ sequence of events.

Presentation format

Poster

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Modeling Assault From Touch DNA

Touch DNA is biological material left behind when an individual has handled an object. Forensic medical examiners are often required to collect biological material from individuals that claim to have been assaulted and is playing an increasing role in solving crimes. This aim of this study was to determine whether the forces applied during a mimicked aggravated assault scenario could be modeled from the DNA collected. Using novel equipment, we investigated the nature of touch DNA transfer, including DNA concentration and subsequent profile generated, when different measures of force are applied and multiple ‘assailants’ made skin to skin contact with a 'victim'. We wanted to determine whether primary and secondary DNA transfer could aid investigators in determining the sequence of events.

Preliminary results have shown that although there was no correlation between the concentration of DNA collected and the average force applied, or the contact time of single strikes, it was possible to determine the sequence of participation when two participants strike the skin pad (one after each other). In 89 % of the samples, the second individual that punched the skin pad was observed to be the major contributor.

This study demonstrates that touch DNA has the potential to determine the sequence of punches when a victim is subjected to multiple strikes by multiple individuals. This information can play a pivotal role in collaborating eyewitness statements and establishing the ‘by who and when’ sequence of events.