ABSTRACT
References ..................................................................................................................................... 181
7.1.1 Radioactive Techniques
Radiographic techniques have been used for €ngerprint development since the 1950s. A good overview of these techniques was provided by Knowles [1]. One of the earliest methods was described by Takeuchi et al. in 1958 [2]. The process involved the use of 14C-labeled stearic acid, which is selectively absorbed by fats present in latent print deposits. Successful results were obtained on substrates like paper, glass, and metal foil. Gel’fman et al. described the use of 14C-labeled formaldehyde to develop latent prints [3]. The process was €rst described and patented by Takeuchi in 1960 [4]. The labeled formaldehyde was thought to react with the amino acids or fatty materials in the print, which could then be imaged using contact radiography.
