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1 A Preliminary Investigation into the Acquisition of Fingerprints on Food Sarah Ferguson, Lynsey Nicholson, Kevin Farrugia, David Bremner, Dennis Gentles * School of Contemporary Sciences, Forensic and Bio Sciences Division, University of Abertay, Dundee, UK * Corresponding Author: School of Contemporary Sciences Division of Forensic and Bio Sciences University of Abertay Dundee DD1 1HG United Kingdom tel: +44 (0) 1382 308110 fax: +44 (0) 1382 308663
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  󰀱 A Preliminary Investigation into the Acquisition of Fingerprints on Food Sarah Ferguson, Lynsey Nicholson, Kevin Farrugia, David Bremner, Dennis Gentles * School of Contemporary Sciences, Forensic and Bio Sciences Division, University of Abertay, Dundee, UK * Corresponding Author: School of Contemporary Sciences Division of Forensic and Bio Sciences University of Abertay Dundee DD1 1HG United Kingdom tel: +44 (0) 1382 308110 fax: +44 (0) 1382 308663 d.gentles@abertay.ac.uk  󰀲 Abstract The potential for enhancement and recovery of latent fingerprints on a variety of foodstuffs has been investigated. In general, black magnetic powder and black powder suspensions appear to be the most successful enhancement techniques with a high number of ridge detail-developed prints over a selected time scale. Banana, apple and tomato surfaces showed enhancement of latent prints but potato and egg surfaces proved to be less successful. Keywords: fingerprint, food, ageing, superglue, powder suspension  󰀳 Introduction  The surface onto which a fingerprint is deposited is often the primary decider as to which technique is selected for enhancement [1]. There is a vast range of such surfaces and specific enhancement techniques are selected based on the surface type and its porosity, the condition of the latent mark and the level of contamination which has occurred. Items of evidence that may retain fingerprints are often overlooked due to the belief that the item in question will not retain any fingerprints. This is mainly due to limited research on ‘difficult surfaces’ such as food, skin and fabric. Singh et al.  [2] determined that fingerprints could be successfully enhanced and recovered from food surfaces such as banana, apple and potato when using black powders although iodine fuming was also successful on apples. A further study by Trapecar and Vinkovic [3] focused on similar fruits and vegetables with some successful results. It was concluded that Swedish Black powder followed by special silver powder yielded the best quality of friction ridge detail and characteristics despite varying surface types. The process of cyanoacrylate fuming was also investigated [3] however results proved less successful. The food items were also graded in terms of their surface suitability with the tomato proving the most appropriate, followed by apple and banana, with the poorest results recorded on potatoes [3]. The surfaces of food items vary greatly not only in their texture and colouration, but also in their porosity and, like any item or surface undergoing development, each of these factors will undoubtedly affect the quality of visualisation achieved. The main aim of this study was to investigate a range of amelioration processes and ascertain which, if any, would be the most suitable for enhancing latent marks on specific food items.  󰀴 Materials and Methods Food Items Three fruits (apple, banana and tomato), three vegetables (onion, potato and pepper) and a dairy product (eggs) were selected as surfaces for testing. All substrates were collected in fresh form, stored in a refrigerator and used within a few days. Prior to fingerprint deposition, the food items were rinsed thoroughly with tap water and gently dried using clean, chemical free blue paper towel to ensure their surface was completely clean and free from any contaminants and unintended fingerprints. Finally the items were allowed to reach ambient conditions for about 24 hours. The food items were then marked off into five clearly labelled sections; one for each of the five fingerprint donors. Following fingerprint deposition, all food articles were stored at room temperature in normal lighting conditions awaiting enhancement at the allocated time intervals Fingerprint Deposition Donor suitability was checked by successful enhancement of fingerprints on a sheet of blank A4 paper with black magnetic powder. Five fingerprint donors were selected: 3 male (donors 1, 2, and 5) and 2 female (donors 3 and 4) who were instructed not to wash their hands at least an hour prior to the deposition of the print. Furthermore, the donors rubbed their fingers across their forehead and nose for about 10 seconds before rubbing their hands together and depositing ‘loaded’ fingerprints for a contact time of less than one second. Fingerprint Grading The following grading system (Table 1) was used to score the quality of ridge detail noted on developed fingerprints following each enhancement process.  Enhancement Techniques The following development techniques were employed during the study: black magnetic powder, superglue fuming, ninhydrin, small particle reagent (SPR), black powder suspension (ready-made), white powder suspension (ready-made), and black powder suspension (freshly-made). To ensure that each chosen development method was working effectively a set of control fingerprints were deposited and enhanced
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