Abstract

Blood, a vital biological fluid, plays an essential role in sustaining life by transporting oxygen and nutrients, eliminating waste, regulating body temperature, and defending against infections. Blood, which is made up of red blood cells, white blood cells, platelets, and plasma, is extremely important for forensic purposes because of its DNA content and capacity to provide information about crimes. Blood at a crime scene can disclose information about the nature of the crime, identity of individuals involved, weapon used, and the sequence of events. Bloodstain patterns, trails, and smears assist in reconstructing the crime scene and determining positions and movements of both victim and perpetrator. In forensic science, blood detection begins with presumptive tests such as the Benzidine, Phenolphthalein (Kastle-Meyer), Leucomalachite Green, and Fluorescence tests. These rapid and sensitive methods rely on the peroxidase activity of hemoglobin to indicate possible blood presence, although they may yield false positives. The Teichmann and Takayama tests, which react with the heme components in blood to generate characteristic crystals, are used as confirmatory tests to verify the existence of blood.Advanced identification methods include Raman spectroscopy, which offers molecular-level insights due to its non-destructive and highly specific nature. Immunoassays, including ELISA and RSID kits, detect blood through antibody-antigen interactions and are increasingly being adapted for field use. Additionally, spectrographic techniques like FTIR and NIR hyperspectral imaging aid in blood stain detection and differentiation from other substances. While blood evidence may not always hold direct legal weight in court, it plays a crucial role in corroborating or challenging testimonies, establishing crime timelines, and linking suspects to crime scenes. Its scientific reliability and interpretive power make it a “silent witness” that significantly contributes to crime investigation and justice delivery.

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