Distinction of Fly Artifacts from Bloodstains in Crime Scenes: A Brief Literature Review

Insect artifacts produced by necrophagous adult flies over a variety of depositional surfaces are problematic in crime scene investigations. Assessment of bloodstains through morphological features combined with contextual and presumptive chemical analysis, as traditional practices, are often inconclusive. Absorbance of bloodstains and substantial wicking on fabrics due to underlying texture and repeated stitch loops in the fabric makes the diagnosis even more difficult than stain morphology. Literature related to the application of modern techniques in the diagnosis of fly artifacts was critically reviewed and presented along with working efficacies and challenges. Apart from the traditional morphological comparison of bloodstains, findings on immunoassay, scanning electron microscopy and DNA-based molecular discrimination have been considered more confirmatory differential diagnosis in crime scenes. Scanning electron microscopic methods reveal distinctive features of small crystal-like deposits with fly artifacts absent in bloodstains. The immunodetection method tested positive with antiserum (anti-md3) against defecatory and regurgitate stains. Moreover, mitochondrial DNA cytochrome c oxidase I (CO1) gene-based molecular diagnosis hold promises in discrimination. However, these modern techniques may be applied along with traditional methods to overcome confusion as per suitability of sampling, following conservative and non-conservative approaches that may offer a real help to crime scene investigators.