The research used the reagent PDT iron (II) to visualize latent imprints formed by the close contact between the metallic parts of the weapons and the palms. The analysis focused on factors that affected the quality of the marks. In addition, PDT analogues were synthesized, and their performance was compared with that of the original compound. Some of the analogues had slight advantages over PDT in contrast and sensitivity. However, PDT in acetone solution, such as in the commercial preparations Ferroprint or Ferrotrace, seems to be the formulation of choice for reasons of availability and cost. PDT in acetone solution can visualize latent firearms impressions on the hands 7 hours, and possibly more, after the contact, provided that the hands have not been washed right after the contact. The recommended procedure is to spray the hand from 15 centimeters. If a mark does not develop within 2 minutes, the hand can be sprayed or washed with water, which may accelerate the appearance of the magenta color and intensify the mark. The hands with the marks are then photographed. Collection of gunshot residue by the adhesive lift method should precede the Ferroprint test. Figures, photographs,and 9 references