Volatilised pyrene: A phase 1 study demonstrating a new method of visualising fingermarks with comparisons to iodine fuming

Abstract

Pyrene is a fluorescent polycyclic aromatic hydrocarbon that can be volatilised under mild conditions. When fumed, pyrene is rapidly absorbed into the sebaceous residues of fingermarks, enabling their fluorescent visualisation upon excitation with ultraviolet radiation. This new means of fluorescent fingermark detection is more sensitive than the non-fluorescent iodine fuming approach for nonporous surfaces. This is demonstrated here in a phase 1 study using split-print comparisons on metal and glass surfaces. Pyrene-treated fingermarks also retain the volatile fluorophore for comparably long time periods relative to iodine fuming (in the order of hours). The phase 1 study comprised four donors, and 80 natural fingermarks that were grouped into two time periods; aged 24 hours and 1 week. Iodine fuming was chosen as a reference to showcase the effectiveness of pyrene given it is the most closely-related chemical fuming method in routine use. This study demonstrates that pyrene fuming increases the quantity and quality of fingermark visualisations relative to iodine fuming, and is free of many of the latter method's drawbacks. Preliminary results shown here also show the effectiveness of pyrene fuming on highly patterned surfaces, and its compatibility with the use of gelatine lifters. Pyrene fuming is thus easy to effect, low-cost, and shows great promise as a new means of visualising fingermarks on non-porous surfaces.

Negative Result: Assessing tropolone and its derivatives as chemical fingermark developers on paper surfaces

“…It is hoped that the chemical insights outlined in this work lead to new chemical strategies and reagents that generate improved contrast and are free of the presented drawbacks. While classed as a negative result, this work complements recent chemical studies in the field of fingermark visualisation, including an analogous negative result using 6-(N,N-dimethylamino)fulvene [14], the successful application of hydrolysed Nile blue A [15], functionalisation of both ninhydrin and 1,8-diazafluoren-9-one [16], the development of nanoparticle reagents [17,18], and the growing number of metal [19][20][21][22], and chemical [23,24], vapour-deposition methodologies.…”

Solvent-free strategies for developing latent fingermarks on paper: a review

“…36 More recently, pyrene sublimation was assessed for copy paper and found to impart blue fluorescence, however this ultimately proved disadvantageous given optical brighteners in paper also emit blue, fluorescent background interference. 50 Pyrene showed a strong interaction with squalene, a major component of sebaceous residue, with limited interaction seen for alanine, a nonpolar amino acid. 50 This strongly suggested that pyrene primarily interacts with the nonpolar components of fingermark residue, namely sebaceous material, and it can be assumed that other polycyclic aromatic hydrocarbons behave in an analogous manner.…”

“…36 More recently, pyrene sublimation was assessed for copy paper and found to impart blue fluorescence, however this ultimately proved disadvantageous given optical brighteners in paper also emit blue, fluorescent background interference. 50…”

“…Pyrene showed a strong interaction with squalene, a major component of sebaceous residue, with limited interaction seen for alanine, a nonpolar amino acid. 50 This strongly suggested that pyrene primarily interacts with the nonpolar components of fingermark residue, namely sebaceous material, and it can be assumed that other polycyclic aromatic hydrocarbons behave in an analogous manner. The anthracene and pyrene fingermark treatments were awarded a TRL of 3, as the efficacy of this treatment was not assessed through validation studies specific to paper.…”

Interpol review of fingermarks and other body impressions (2019 – 2022)

“…Preliminary/Pilot studies – The following compounds were synthesized and successfully applied to sebum-rich fingermarks: dialkylated NB and NR derivatives [ 374 ], purine derivatives [ 375 ], and fumed pyrene [ 376 ]. The combination of iodine fuming with hexane or chloroform spraying was presented to detect fingermarks on various substrates [ 377 ].…”