A Preliminary Study on Vacuum Metal Deposition as a Standalone Method for Enhancement of Fingermarks on Ballistic Brass Materials

Abstract

In order to assess the efficacy of vacuum metal deposition (VMD) as a technique to develop fingermarks on ballistic metallic surfaces, a preliminary study using six donors (three male & three female) was conducted. Using a sequential metal deposition process, two metal combinations were studied—gold/zinc and silver/zinc. Results indicate the potential of this technique, by developing identifiable fingermarks on brass metal disks aged from a few days up to more than a month old. As the development of fingermarks on fired (brass) cartridge cases is an area of interest, a further study was conducted where a total of 20 fingermarks were deposited on cases. After firing, second level fingermark characteristics were successfully observed on cartridge cases highlighting its potential as a fingermark enhancement method for ballistic brass materials. Further work is required to fully evaluate the VMD process and its reliability as a fingermark enhancing method on ballistic surfaces.

Vacuum metal deposition enhancement of friction ridge detail on ballistic materials

“…Therefore, the fingermarks of donors who produce large quantities of these components may not develop effectively thus producing the poor-quality marks. Their study also exposed marks to a higher vacuum and a longer time than during a VMD treatment, meaning that vacuum effects in our study may not be as prevalent [20,23].…”

“…VMD involves evaporation and deposition of a variety of metals, most commonly gold or silver, followed by zinc, within a high vacuum chamber [20]. The initial metal forms a thin film across the entire surface made up of small clusters of the metal atoms.…”

“…Research is now focussing more specifically on the use of VMD for ballistic evidence. A recent study by Christofidis et al [20] found that both Gold/Zinc and Silver/Zinc VMD were able to enhance potentially identifiable FRD on ballistic brass tiles, and produce second level FRD on cartridge cases after firing. Although the study used only six donors, the results indicate that VMD may be an effective technique for the development of FRD on ballistic evidence.…”

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

“…Other sections – The following papers are detailed in other sections of this report: ability of VMD to detect fingermarks on brass plates and fired cartridge cases [ [267] , [268] , [269] , [270] , [271] ] – See Section 4.4.4 ; performance of the sequential processing involving VMD and amino acid reagents on thermal papers [ 272 ] – See Section 4.4.5 ; impact of corrosive substances on fingermark recovery [ 273 ] – See Section 4.5.3 .…”

“…VMD – A series of preliminary studies (few donors and/or sebum-rich fingermarks) investigated the ability of VMD to be applied on brass plates and fired cartridge cases [ [267] , [268] , [269] , [270] , [271] ]. Given their preliminary nature, all these studies require further experiments to strengthen their conclusions, which were the following: positive results were obtained with VMD Au/Zn and VMD Ag/Zn [ 268 , 270 ], both studies emphasizing the influence of the donor and the detrimental impact of the firing event. In her comparative studies, Brewer concluded that VMD Al suited best brass rifle cartridge casings [ 267 ], VMD Au/Zn – wad shotgun cartridges [ 267 ], and VMD Ag – brass handgun casings [ 269 ].…”