Forensic Department "Environment-Fire-Explosives"
Forensic Expert - Forensic Department "Environment-Fire-Explosives", IRCGN
In order to fight against robberies and aggressions having villainous purpose, taggants technology, coming from the fight against counterfeiting, burst in the domain related to security. Those innovative products are available under several commercial solutions (grease, gel, liquid, varnish, spray, each of these types corresponds to a dedicated application) and contain each a chemical or biological code whose uniqueness is guarantee by the supplier.
Since 2011, the IRCGN has established an analytical strategy dedicated to identify those discriminating codes. This strategy involves different analytical techniques depending on the integrated code: mineral chemical elements, synthetic DNA sequence, metallic or polymeric micro particles.
The identification of the taggants type (supplier and the code technology) is obtain thanks to the use of a dedicated lamp, except the stained ink for banknotes which visual presence is already explicit.
Cases treated at the IRCGN since 2011 have allowed the testing of the established strategy, as much on chemical codes as on biological ones.
The application of this analytical strategy is function of the observation of the targeted object.
Depending on a specific fluorescence highlighted (observed colour) by the dedicated lamp, analysis is leading towards either an LA-ICP-MS analysis or an analysis by pyrosequencing, sequencing or genotyping, in order to reveal the specific product’s code. If micro particles are observed as well as fluorescence, an observation of those under binocular magnifier allows the code identification of the product used. Indeed, each of those micro particles are engraved with a laser on one of its sides.
In the case of a stained product, concurrently with the analysis of the colorant undertaken by the LC-HR-MS, a first study with the MEB-EDS is made in order to notice any potential chemical marker. If the result is negative, a study to analyse the presence of biological markers is realised by pyrosequencing or genotyping.
Once the chemical or biological code is identified, the serial number corresponding to the code will be indicated on the report that will be handed over to the applicant.
In each of those cases, consulting an internal database allows to link the number with facts and/or the device location, shaping thus a real added value to the judicial investigation.
Discriminating code, Material evidence, Taggants