Using Infrared Photography to Document Clothing Evidence in the Reconstruction of a Homicide
Background on Infrared Photography
The use of infrared (IR) photography in forensic casework has been well documented in the forensic literature. It has primarily been used for the documentation of gunshot residue patterns and blood staining on dark colored clothing (1, 2), although it has also been used for the photography of latent tattoos and for the characterization of different types of inks. The principle behind the infrared photography of blood stains is that many dyes and fabrics reflect a large amount of infrared radiation, whereas blood stains absorb most wavelengths of visiblelight (400-700 nm) and near infrared light (700-900 nm). This results in the fabric appearing gray or white with the contrasting blood staining darker in color. The enhanced contrast between the fabric and the evidence (blood) allows the examiner to better interpret the evidence and assists in sample selection for further testing (i.e. phenolphthalein, DNA). This technique is especially useful due to its non-destructive nature, its lack of