title: Comparison of practical techniques to develop latent fingermarks on fired and unfired cartridge cases.
abstract: We have tested some widely used and practical fingermark enhancement techniques such as powdering (regular powder dusting and magnetic powder application), cyanoacrylate fuming, fluorescent dying (basic yellow 40), gun blueing solutions and acidified hydrogen peroxide solutions. The results were evaluated and compared in order to establish best procedures on processing cartridge cases. The tests were performed on brass discs subjected to three different temperatures (room temperature, 63 and 200°C), and on fired and unfired cartridge cases. All the samples were processed after three different periods of time (24h, 7 days and 14 days) after deposition. The best results for both fired and unfired cartridge cases were obtained by the sequential application of cyanoacrylate, gun blueing solution and basic yellow 40. Some stages of the firing process were isolated in order to identify their effects over the final amount and quality of the remaining latent fingermarks on cartridge cases. Good state fingermarks were developed on unfired cartridge cases cycled through the gun, showing that friction inside the gun without firing does not cause significant damage to the fingermarks. On the other hand, fired cartridge cases are significantly affected by the firing effects, exhibiting low quality ridge details which are mainly located next to base. An unexpected phenomenon was observed on most of the brass discs heated to 200°C and developed with gun blueing solutions; they presented a reverse development compared to the expected one, with darkening of the ridges instead of the background.
authors.affiliation: Laboratory of Carbon and Ceramic Materials, Department of Physics, Federal University of Espirito Santo, 29075-910 Vitoria, ES, Brazil; Identification Group, Federal Police Department of Brazil, 29114-670 Vila Velha, ES, Brazil. Electronic address: girelli.cmag@dpf.gov.br.
authors.forename: Carlos M A
authors.initials: CM
authors.lastname: Girelli
authors.affiliation: Identification Group, Federal Police Department of Brazil, 79904-644 Ponta Pora, MS, Brazil.
authors.forename: Bernardo J M
authors.initials: BJ
authors.lastname: Lobo
authors.affiliation: Laboratory of Carbon and Ceramic Materials, Department of Physics, Federal University of Espirito Santo, 29075-910 Vitoria, ES, Brazil.
authors.forename: Alfredo G
authors.initials: AG
authors.lastname: Cunha
authors.affiliation: Laboratory of Carbon and Ceramic Materials, Department of Physics, Federal University of Espirito Santo, 29075-910 Vitoria, ES, Brazil.
authors.forename: Jair C C
authors.initials: JC
authors.lastname: Freitas
authors.affiliation: Laboratory of Carbon and Ceramic Materials, Department of Physics, Federal University of Espirito Santo, 29075-910 Vitoria, ES, Brazil.
authors.forename: Francisco G
authors.initials: FG
authors.lastname: Emmerich
mesh_terms: D003300:Copper; D003487:Cyanoacrylates; D003878:Dermatoglyphics; D005389:Firearms; D005456:Fluorescent Dyes; D006801:Humans; D006861:Hydrogen Peroxide; D008855:Microscopy, Electron, Scanning; D011208:Powders; D012997:Solvents; D013696:Temperature; D014835:Volatilization; D015032:Zinc
chemical_list: D003487:Cyanoacrylates; D005456:Fluorescent Dyes; D011208:Powders; D012997:Solvents; C048399:brass; D003300:Copper; D006861:Hydrogen Peroxide; D015032:Zinc
keywords: Basic yellow 40; Cartridge case; Cyanoacrylate; Fingermark; Gun blue; Reverse development