Author(s): Kobus HJ, Edmund Silenieks, Jordana Scharnberg
The paper describes the use of the Polilight, a light source based on a xenon arc lamp, to exploit the fluorescence properties of semen as an aid in searching fabrics for stains in sexual assault cases. The broad excitation spectrum of semen allows the fluorescence to be generated at a range of wavelengths. This permits selection of excitation and emission conditions that minimize interference from background fluorescence of the fabric, thereby optimizing the contrast between fabric and stain. A common method of observing fluorescence is by using colored plastic goggles or filters. The paper describes modifications to goggles for casework applications. The paper cautions that fluorescence cannot be used in isolation for semen detection but provides a valuable screening technique when used in conjunction with other methods.