Analyses of forensic vacuum metal deposition samples using atomic force microscopy

Forensic vacuum metal deposition (fVMD) is a well-known, well-regarded technique in forensic fingermark development whose underlying mechanism remains unclear. By taking a fundamental scientific approach and probing the question using atomic force microscopy, the authors have demonstrated that, when gold is deposited directly onto stearic acid in fVMD mono-metal development conditions, the gold nanoparticles are on the surface of the matrix and have not been absorbed. This disproves the currently held models regarding the mechanism of development of fVMD. Based on the results, the authors present an alternate model of fVMD development; adatom diffusion.