SPECTROPHOTOMETRIC ACCURACY OF PRESUMPTIVE TESTS FOR BLOOD STAINS ON VARIOUS SUBSTRATES – AN OBSERVATIONAL STUDY
DOI:
https://doi.org/10.48165/jfmt.2024.41.2.19Keywords:
Blood composition, Forensic science, Bloodstain detection, Sensitivity analysis, Spectrophotometric methods, Crime scene investigationAbstract
This study focuses on assessing the spectrophotometric accuracy of presumptive tests for detecting bloodstains on various substrates, a critical aspect of forensic science in violent crime scene investigations. Blood, a complex substance rich in proteins and enzymes, serves as vital evidence but can deteriorate, posing challenges during forensic analysis. This research aims to address these challenges by evaluating the sensitivity and persistence of bloodstains on surfaces such as glass, tile, wood, cardboard, and linen over time.Utilizing three presumptive tests Phenolphthalein, Benzidine, and Leucomalachite Green and confirmatory tests Teichmann and Takayama this study investigates the efficacy of these methods over a period of up to nine weeks. Samples were subjected to spectral analysis to determine absorbance and track changes in reactivity. Initial findings reveal strong positive reactions from all tests up to three weeks, indicating high sensitivity. However, Leucomalachite Green exhibited a notable decline in sensitivity beyond the initial period, reflecting its limitations in long-term detection scenarios. Conversely, Benzidine and Phenolphthalein tests demonstrated consistent performance over extended durations, particularly on non-porous surfaces like glass and tile, which also showed the highest mean absorbance values in the spectrophotometric analysis. The Takayama confirmatorytest emerged as particularly reliable, maintaining strong positive results even after nine weeks, unlike the Teichmann test, which showed reduced sensitivity at later stages. This comprehensive evaluation highlights the critical role of substrate material and aging in influencing test outcomes, emphasizing the need for careful selection of testing methodologies in forensic contexts. The insights gained from this study can significantly enhance the accuracy of forensic blood detection and the development of optimized protocols, thereby improving crime scene analysis and supporting effective criminal investigations. These findings pave the way for future research and methodological refinements in forensic science.
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