Trace evidence is arguably the most demanding of forensic disciplines as we are asked to find the tiniest specks of material in a mist of very similar looking background.

The size and complex nature of the material of interest, combined with the requirement that we must be as non-destructive as possible in our pursuit of information, challenges the most skilled scientists and hi-tec equipment.

Microscopy and spectroscopy form the core of the battle to obtain the information we need without damaging the sample. At Contact Traces we are the first forensic laboratory in Great Britain to routinely use Raman Microspectroscopy in trace evidence. The technique has been shown to provide increased intelligence in forensic fibre analysis, and increased discriminating power in paint analysis.

FTIR microspectroscopy also plays an important, more traditional means of analysis, and in combination with Raman microspectroscopy, means that full spectroscopic characterization of materials can be provided. We currently use Thermo iN10 FTIR and Thermo DXR dispersive raman microscopes, the fastest mapping instruments on the market. In particular Thermo's patented Omnic Picta software is a good tool for discriminating spectra of complex mixtures. We have the most important commercial spectral libraries, and the ENFSI EFG raman dye database. We also build our own in-house libraries, including one containing over 700 paint pigments and related compounds. All casework materials analysed by FTIR and Raman are added to the general casework library.

As part of Oxford University’s Begbroke Science Park we also have access to the full range of specialist techniques on offer by Begbroke Nano. Trace evidence is so diverse an area that from time to time cases require non-routine analysis, such as the imaging of surface textures of fibres, nanomaterials. Please check out our technical notes page for case studies showcasing some of these analyses.