Vacuum Metal Deposition
Vacuum Metal Deposition (VMD) is one of the most powerful latent fingermark development techniques available. The technique is widely used to develop latent fingermarks on non-porous, semi-porous and porous exhibits. Fingermarks developed using VMD are often much higher quality with excellent contrast and ridge clarity.
The standard VMD process employs the sequential vacuum deposition of a very thin layer of gold followed by a thin layer of zinc. However, in response to the introduction of more recycled and biodegradable plastics, exciting new forensic research has led to the expansion of the technique to include single metal deposition processes e.g. silver, sterling silver, copper and aluminium and new multi-metal deposition processes e.g. gold/zinc/silver or silver/zinc.
VMD has developed latent fingermarks on evidence that is over 20 years old. The technique has also provided remarkable results on exhibits that have been submerged in water or buried underground.
Key research has shown that VMD can develop fingermarks on tight weave fabrics. In addition VMD can identify contact areas, e.g. grab impressions, on fabrics with a loose weave, with the possible application to aid targeted DNA swabbing/extraction.
Fingermarks developed by VMD are of a much higher definition (often to 3rd level detail) and have superior contrast than marks developed using the cyanoacrylate fuming technique. The VMD process can also be used sequentially with other traditional techniques making it ideal for cold cases which have been previously processed.
VMD is an optimal technique for a wide range of exhibits, including flexible plastic packaging, plastic bottles, glass, fabrics, firearms, glossy paper, thermal paper, polymer & paper banknotes, wood etc.
The VMD technique is very rapid (typically less than 10 minutes) and produces results that can be photographed straight away. Additional to this, the standard technique is very stable, developing fingermarks that will not fade and can be imaged many days later.
A number of alternative lighting techniques have been identified as excellent ways to further enhance VMD developed fingermarks. Reflected infrared imaging and co-axial lighting have both shown to improve marks developed on complex and reflective substrates.