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In this work we demonstrate a composite material based on silica particles. The particles have been doped with zinc oxide quantum dots which possess long living luminescence. The surface of the particles has been functionalized with phenyl groups using sol-gel process. The new material has been successfully applied for visualization of natural latent fingermarks on several surfaces, in particular, those showing their own luminescence and intensive background staining while using powder dusting, what is of the vital interest of forensic science. The time-gated imaging allows to overcome the background luminescence problem and surface functionalization increases the affinity of the particles to the fingermarks, what improves the selectivity of a new developing agent. The main novelty of the presented approach is the use of composite material that combines two main features—long lifetime luminescence and the ability to preferentially attach to the fingermark, due to hydrophobic interactions. Moreover,the utilization of deposition from the suspension instead of simple powder dusting allows for development of latent fingermarks on the surfaces that are difficult to work with powders (e.g. sticky side of the adhesive tape).

We introduce a new latent fingermark (LFM) development method, where compounds showing long lifetime luminescence are generated in situ by the reactions of Eu­(TTA)3(H2O)2 with LFM components. Until now, time-gated imaging could not be used to develop LFM on porous surfaces due to the difficulties with selective binding of the developing agents to the fingermark ridges. The nature of the interactions of Eu­(TTA)3(H2O)2 with the LFM material has been investigated for three model compounds commonly found in the LFM compositionoleic acid, l-serine, and squalene. The LFMs developed with the europium β-diketonate complex have been successfully photographed using a time-gated imaging scheme. The presented new approach has been demonstrated to give similar or better results than developing agents commonly used for paper samples (ninhydrin and 1,2-indanedione). Moreover, contrary to the methods mentioned above, the new approach allows for the development of amino acid-poor LFM on paper.

The article presents the results of studies on the method of sensibilizing dactyloscopic traces directly from the gaseous phase. The detection of dactyloscopic traces on absorbtive surfaces requires specific revealing methods, whose essential aspect is the need to deliver reagent to the place of occurrence of the corresponding component of trace forming substance. In practice, for many years, various types of solutions have been used for this purpose, such as DFO, ninhydrin and 1,2-indanedione. Within the framework of this study, research was carried out on revealing fingerprints on absorptive surfaces with the use of genipin, under reduced pressure conditions and in order to compare against the liquid phase. Based on the results of the tests carried out and results obtained, it should be stated that the genipin vacuum sublimation technique can be successfully used to reveal fingerprints on absorptive surfaces. The traces revealed are visible both under white light and fluorescence illumination. The effectiveness of the dactyloscopic trace sensibilization method in the gaseous phase has been demonstrated with regard to such substances as ninhydrin and genipin.

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