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Enhancement of latent fingermarks found at crime scenes can be crucial to criminal investigations. The performance of ninhydrin analogues 1,2-indanedione (IND/Zn) and 1,8-diazafluoren-9-one (DFO) used in laboratories for the enhancement of latent fingermarks on porous substrates were compared for operational use. The visualisation of enhanced latent fingermarks on seven substrates commonly encountered in local crimes - plain A4 paper, glossy magazine, paper magazine, brown envelopes, white envelopes, cardboard, and joss paper were assessed using fingermarks deposits from seven donors. Fingermarks were aged under both indoor and outdoor conditions as well as over different periods of time. Our results show that IND/Zn consistently produced fingermarks of superior quality and contrast to DFO across the different donors, substrates and time periods. IND/Zn also appears to be more sensitive compared to DFO., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

1,2-indanedione (1,2-IND) and 1,8-diazafluoren-9-one (DFO) are used in the forensic field to enhance latent fingerprints deposited on porous surfaces due to the formation of fluorescent products by reacting with the amino acids present in the papillary exudate. The study was carried out in collaboration with the Fingerprints and Photography Section of the Carabinieri Scientific Investigation Department (RIS) of Rome, in which laboratories, until now, DFO has been the most used because of its excellent enhancing properties, even if it is more expensive and relatively toxic in comparison with the 1,2-IND. The aim of this work was then to evaluate and to compare the effectiveness of three solutions of 1,2-IND in different formulations and a DFO solution employed as single enhancing treatments, in order to assess whether it was possible to replace a reagent with the other obtaining equally satisfying results. In this case, white office paper was selected as deposit surface since it also permitted one to observe those reaction products that appear visible to a naked eye. Beside to a qualitative study of the visual characteristic of the enhanced fingerprints, further quantitative studies were conducted on the intensity of fluorescence of the products and on the consumption of amino acids during the reaction. The analyses, which at first were conducted on standard samples, were then repeated on real samples to validate the results obtained. The DFO confirmed its excellent enhancement properties, but also one of the three solutions of 1,2-IND showed comparable properties in terms of enhanced fingerprint definition and stability over time from the completion of a crime. As a result, we proved that a selected 1,2-IND formulation may replace with satisfactory achievements the DFO solution currently employed, providing also advantages from the point of view of safety and cost savings., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

A new method for improved development of latent fingermarks on thermal paper by 1,8-diazafluoren-9-one (DFO) treatment is described. Compared with conventional DFO solution, the mixed solution of DFO/PVP (polyvinylpyrrolidone) described here reduces black background staining without removing the thermosensitive layer and develops fingermarks by the reaction of DFO with amino acid deposited on the thermal paper's surface. An advantage of this approach is that the developed fluorescent fingermarks have high contrast and can be observed and photographed when excited in the 515 nm region and observed through an orange-red barrier long-pass filter with no background coloration. In addition, the method reported here does not involve any pre- or post treatment of the substrate and exhibits high sensitivity with good stability. Experimental results showed that the method was able to develop very old fingermarks, up to 154 days old, demonstrating the feasibility of using the method to develop identifiable latent fingermarks operationally. Furthermore, we extended our experiments to various types of thermal papers. Notably, this method exhibits several very attractive features, namely time saving, simple procedures, inexpensive, convenient operation, and PVP is non-toxic and reasonably priced. Finally, in this study an attempt has been made to explain the reaction mechanism of the process and the effects of PVP., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

A new method for enhancement of ninhydrin or 1,8-diazafluoren-9-one (DFO)-treated latent fingerprints on thermal paper will be described. Most thermosensitive surfaces of thermal paper become dark when treated with DFO or ninhydrin petroleum ether (NPB) solution. This effect minimizes contrast between the developed fingerprints and the background. The new method described reduces this dark staining without removing the thermosensitive layer and parts of the developed fingerprints, as occurs with acetone washing. Through the new method, the developed fingerprints appear in sharp lines and high contrast. Extensive tests were performed, leading to an optimized working solution, which charges the paper with a minimum of chemicals, is cheap, and enables a large quantity of papers to be treated in a short time. The working solution contains commercially available, nonvolatile, nitrogenous organic compounds and can be used like the application of NPB solution by dipping.