The evidential value of cosmetic foundation smears in forensic casework

Cosmetic foundation products are easily transferred to clothing and other surfaces as a result of contact with such objects. Examination of past cases involving cosmetics in New Zealand has shown cosmetic foundation to be one of the more common cosmetic products encountered. The aim of this research was to determine the most discriminating method for the comparison of transferred foundation with samples obtained from a known source in forensic casework. Fifty-three foundation samples were analyzed by Fourier transform infrared spectroscopy (FTIR), gas chromatography with a flame ionization detector (GC-FID) and scanning electron microscopy-energy dispersive X-Ray analysis (SEM-EDX). It was found that a 5 mm2 section of a light smearing was enough to provide detectable results. The discriminating powers for FTIR, SEM-EDX and GC-FID were 98.3, 93.8, and 82.0% respectively. A combination of all three techniques provided a discriminating power of 99.7%, meaning that almost complete discrimination was achieved between the foundation samples.