Optimizing parameters for the use of alternate light sources in detecting fragmentary bones: a pilot study

Recent studies have suggested that alternate light sources (ALS) are effective in detecting bone and teeth fragments at crime scenes. These studies, however, are few in number and provide no consensus as to the optimum combination of wavelength and filter for best detecting bone from non-bone material. Additionally, each study has been conducted using different environments, bone species and varying degrees of exposure to taphonomic factors. The aim of this study was to investigate the optimum parameters of ALS for the detection of bone and teeth fragments in a laboratory setting. Human and non-human bone, and tooth fragments were compared with non-bone material using handheld Rofin Poliflares. Temperature-treated bones (frozen, boiled and burnt) were included to assess if taphonomic factors affected fluorescence. Wavelengths ranging from 415 nm-530 nm were used and fluorescence was recorded using photographic images, and intensity analysed in ImageJ. Results of this pilot study found that the 450 nm Poliflare with orange filter provided the best discrimination of bone/tooth versus non-bone when used at a distance of up to 100 cm from the objects. Fluorescence of heat-treated bones is weakened at distances greater than 30 cm, which should be taken into account when temperature modification to remains is suspected.