Wang Ming-cha
2015
Citations
0
Influential Citations
1
Citations
Journal
Forensic Science and Technology
Abstract
Objective Paper is frequently encountered in crime scene, with deposited fingerprints containing grease or oil on its surface. Physical developer and Oil Red O, as two effective ways to develop these fingerprints, have been used in case work abroad, both of which can color the friction ridge by combining with substance in fingerprint residues especially the oil or grease, consequently making the latent fingerprint visible. However, the two methods have not drawn enough attention in domestic forensic practice. This paper explores the potential advantage of physical developer and Oil Red O respectively in order to provide a reference for the forensic scientific research and crime investigation. Methods Natural fingerprints ranging from strong to weak(‘depletion' prints) selected from eight donors randomly were sequentially deposited on strips of common copy paper, pink copy paper, thick white copy paper, thick kraft paper, thin kraft paper, fax paper, thermal paper, offset paper, pressure-sensitive paper, newspaper and scratch paper. In order to observe the obvious contrast, the ‘split print' approach was used by cutting the strips from the middle of the developed prints into two parts for physical developer and Oil Red O. Samples treated with physical developer were immersed into the maleic acid, distilled water, the working solution and distilled water sequentially. Those treated with Oil Red O were immersed into the dyeing solution and p H 7 buffer. The developed fingerprints were divided into four grades according to the quality of the developed friction ridges, and the comparison was also based on this scale of score standard. Results The principles of coler reaction by the two solutions differed in the color combination between the particles and fingerprint's residues left on paper surface. The quantity and quality of fingerprints developed by both Oil Red O and physical developer were affected with sample exposure, the solution processing environment, the operating conditions and other factors. Ten different papers showed different development results. Oil Red O displayed some advantages over physical developer according to the comparison of the solution preparation, operational aspects as well as the final results. Conclusions Oil Red O method is superior to physical developer and has good application prospects in fingerprint development.