The use of ortho-Phenylenediamine and Zar-Pro™ strips for the development of bloodmarks on a dark-coloured, non-porous surface

The development of fingerprints in blood on a dark-coloured surface can be difficult. Contrast between the bloodmark and the surface can be difficult to achieve using photography and chemical reagents. The use of haem-reagent ortho-Phenylenediamine (OPD) and Zar-Pro™ strips in the enhancement of bloody impressions were investigated. Depletions of bloodmarks were deposited on black ceramic tiles and aged up to 90 days. OPD, Acid Yellow 7, and Hungarian Red were applied to these tiles and the developed fingermarks were compared using a numerical score system. Zar-Pro™ strips were applied to chemically treated and untreated bloodmarks alike. OPD proved to be effective at developing bloodmarks aged up to 90 days, including latent marks. Despite this capability, OPD did not perform as well as Acid Yellow 7 and so the continued use of Acid Yellow 7 is recommended. Zar-Pro™ strips were able to lift bloodmarks aged up to 90 days as well as those chemically treated with either: OPD, Hungarian Red, Acid Yellow 7, or Amido Black although ridge detail was poor. Additional investigation into the capabilities of Zar-Pro™ strips for this purpose is recommended.