Avaliação das modificações químicas nos fragmentos de impressão digital e cocaína depositados na superfície de estojos de armas de fogo, após disparo

Abstract

The literature describes that high firing temperatures would be sufficient to degrade chemical substances present in fingerprints, including lipids, cocaine and cocaethylene. In this sense, it is important to know if these substances are degraded after firing. In this study, 38 caliber cartridges were doped with lipids, fingerprints, cocaine and cocaethylene, part of the cartridges had these substances extracted without being fired and part after being fired. The amount of analytes present before the shot was compared with the amount of analytes present after the shot through Student's t-tests and the F test, with 95% confidence and no major statistically significant differences were found in the amount of these analytes, with the exception for the squalene lipid, which had its concentration reduced by 28% after the shot. The lipids tested were myristic acid, pentadecanoic acid, palmitoleic acid, palmitic acid, stearic acid, squalene and cholesterol. Developers of the “quantum dots” type were also tested and compared to the development with rhodamine and basic yellow. The “quantum dots” tested improved the development with cyanoacrylate, but showed a lower result than the development with cyanoacrylate and basic yellow/rhodamine. The results of the work demonstrated that the importance of cartridge temperature in the loss of fingerprint quality due to lipid degradation would be reduced, other factors such as cartridge friction with the internal parts of the weapon, soil and evidence bag wall could have greater relevance in the digital destruction process.