Vacuum metal deposition (VMD) – characteristics of the method

Abstract

Vacuum metal deposition was introduced in the process of visualization of latent fingermarks already in the 20th century. However, due to the requirement of using specialist equipment to ensure appropriate conditions for the development process, which would have generated significant costs, the method was not available in Poland. Technological developments, however, made it possible to create compact devices with smaller dimensions and lower parameters, which, nowadays, can be used in virtually every forensic fingerprint identification laboratory. The article describes the theoretical basis of the process of developing fingerprints by means of the vacuum metal deposition method with the use of sequential deposition of gold, zinc and silver on the tested surfaces. The device used for the VMD method is also presented along with sample effects of treating fingerprints on various surfaces, including registration in the range of reflected infrared light and with recovering marks on lifting foils. The final part deals with the issue of accrediting forensic service providers performing fingerprint examinations, including problems related to the implementation of vacuum metal deposition in the range of accredited fingerprint visualization techniques.