Abstract
Locard’s principle states that “every contact leaves a trace,” meaning that physical evidence is left at the location of a crime. The collection of this information is a crucial step in solving a crime. If this evidence cannot be located, then it cannot be collected. Smells in the form of volatile organic compounds (VOCs) are a potential source of evidence that is currently underexplored, and because of their nature, standard evidence collection procedures are not appropriate for them.This project aimed to address this through the development of a standard operating procedure (SOP) for the collection of VOCs at the crime scene.
A range of activated carbons (ACs) called Chemviron , Audew, and Mondado were tested using standard chemicals (commonly found in decomposition) and analysed by Headspace-Gas Chromatography-Mass Spectrometry (HS-GCMS). A different wight include 10 mg, 20, mg, and 30 mg from the activated carbon was tested initially to collect the standard chemicals to use for optimising a sampling parameter, including active and passive sampling, and to develop a collection device to be deployed at the crime scene.
The results of this method development were used to write an initial SOP, which was further tested and evaluated. The three types of tested experiments were performed in the laboratory with the standard chemicals, for comparison (Direct onto carbon – 0.5 µl, Mixed – 200 µl, and Individual – 1000 µl) of each standard ( Section 5.5.2 ) and were left at room temperature for 3 hours to allow the VOCs to generate before collection procedure outlined in the SOP. This preliminary evaluation of the SOP suggested that its basic form was functional when used and repeated by the researcher.
The evaluation process included testing using a laboratory setting with standard chemicals and volatile samples likely to be at the crime scene including accelerant, perfume, E- cigarette liquid, and decompositions. the results of this study indicate that the SOP shows promise in the collection of a wide range of VOCs that could be encountered during forensic investigations with Some of the limitations may result from the carbon chosen rather than the collection procedure.
After this, testing moved onto a simulated crime scene setting, where SOP blind tested.
All these results were used to refine the SOP for the into its final form. The aim is to develop a SOP to collect VOCs at the crime scene despite some limitations, shows promise.
| Date of Award | 7 Jun 2024 |
|---|---|
| Original language | English |
| Supervisor | Natasha Reed (Main Supervisor) & Gareth Parkes (Co-Supervisor) |