Fluorescence of 1,2‐Indanedione with Amino Acids Present in the Fingerprint Residue: Application in Gender Determination

1,2‐indanedione is used for latent fingerprint visualization on porous surfaces. In this paper, fluorescence spectra of 1,2‐indanedione after reacting with 21 individual amino acids present in latent fingerprints residue were measured in water‐methanol solutions. The fluorescence intensity depends on the amino acid used, while the fluorescence peak does not change much. The concentration of amino acids in fingerprint residue in females is almost the double of their concentration in males. This property combined with fluorescence of 1,2‐indanedione‐amino acids compounds is used for gender determination, by comparing the fluorescence intensity peaks in the same experimental conditions. In this preliminary study, the fluorescence signal from the samples representing females was almost two times the signal for samples representing males. In addition to the reduction by almost 50% of the number of suspects in a criminal research case, these results could be helpful in gaining some knowledge about the papillary residue composition.     

Enhanced Visualization of Latent Fingermarks on Rough Aluminum Surfaces Using Sequential Au and Zn/ZnS/ZnO Depositions

Detection and visualization of fingermarks on rough and diffuse surfaces is a relatively challenging task. We succeeded in developing latent fingermarks on scratched and rough aluminum surfaces by sequential deposition of a thin layer of gold followed by one of zinc or zinc‐based compounds on the fingermarks. The best image enhancement was achieved with sequential Au and ZnS depositions. Using this combination, we could enhance the visualization of latent fingermarks aged over 65 days in normal conditions. The optical reflectance from the fingermarks with the deposited layers of metal/dielectric is analyzed as a stratified medium. Significant contrast in the reflectance from the regions of the ridges and the valleys of the fingermark would enhance the visualization. Our results show that the Au and ZnS bi‐layer combination can have a large reflection contrast and improved fingermark visualization at wavelengths corresponding to the green light for specific thickness of ZnS.     

Mass spectra and time-resolved fluorescence spectroscopy of the reaction product of glycine with 1,2-indanedione in methanol

The reaction products of 1,2-indanedione (a new fluorescent fingerprint reagent) with glycine in methanol, at room temperature have been studied using excitation and emission and time-resolved fluorescence spectroscopy. Gas chromatography-mass spectroscopy (GC/MS) has also been used to determine which compounds are formed. Reaction products were identified using GC/MS as 2-carboxymethyliminoindanone (MW=203 g) and 1,2-di(carboxymethylimino)indane (MW=260 g). Identified compounds show room temperature fluorescence lifetimes of tau(1)=7.69 ns and tau(2)=1.27 ns. It is not clear yet which compound is having fluorescence lifetime of 7.69 ns and which one is showing 1.27 ns.