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The origin of unknown source DNA from touched objects.

Alycia K Buckingham¹, Michelle L Harvey², Roland A H van Oorschot³

¹Deakin University, School of Life and Environmental Sciences, Centre for Chemistry and Biotechnology, (Waurn Ponds Campus), 75 Pigdons Road, Locked Bag 20000, Geelong, Victoria 3217, Australia; Office of the Chief Forensic Scientist, Victoria Police Forensic Services Department, Macleod, Victoria 3085, Australia.

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Summary

This summary is machine-generated.

DNA transfer on shared objects like knives is complex. The last person to touch an object may not leave the most DNA, and foreign DNA can be transferred between handlers.

Keywords:

DNA transfer Knife handle Non-self DNA Touch DNA Trace DNA

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Area of Science:

Forensic Science
Molecular Biology
Trace Evidence Analysis

Background:

DNA evidence is crucial in criminal investigations.
Limited data exists on DNA transfer and persistence after multiple handlings.
Understanding DNA deposition and pickup from shared objects is vital.

Purpose of the Study:

To investigate DNA transfer and persistence on a knife handle after sequential handling.
To examine DNA deposition on clean surfaces after touching a previously handled knife.
To assess the contribution of different handlers to the final DNA profile.

Main Methods:

Simulated multiple handlings of a knife by different individuals.
Collection of DNA profiles from knife handles.
Analysis of DNA transfer to subsequent objects (handprints on flat surfaces).

Main Results:

Later handlers' DNA profiles are often more prominent than earlier handlers'.
The last handler is not consistently the major contributor to the DNA profile.
DNA pickup and transfer occur readily, but diminish with subsequent handling.

Conclusions:

DNA profiles from shared objects reflect complex transfer dynamics, not just the last handler.
Individual handling patterns and sequences significantly influence DNA contributions.
Caution is necessary when interpreting mixed DNA profiles from sequentially handled items.