Detection of Latent Fingerprints on Fruits and Vegetables

Transcription

1 Technical Note Detection of Latent Fingerprints on Fruits and Vegetables Gagan deep Singh 1 G. S. Sodhi 2 O. P. Jasuja 1 Abstract: Latent fingerprints are a common and important form of physical evidence at crime scenes. These latent fingerprints may be present on a variety of objects, including the surfaces of fruits and vegetables. This study was conducted to determine the best procedure for developing latent fingerprints on fruits and vegetables. Powders were able to develop latent fingerprints with very high quality. The iodine fuming method did not yield good results. Introduction Despite advances that have been made in personal identification (e.g., DNA profiling), fingerprints are in the forefront of criminal investigations. Fingerprint detection has acquired a new dimension because of the emergence of newer technologies (e.g., lasers and advanced chemical processing formulas). Because latent fingerprints are chance prints, they can be encountered on a variety of surfaces, ranging from nonporous to porous. Using black, copper, and gray powders, much research has been conducted on nonporous surfaces (e.g., glass) for the development of latent fingerprints [1]. The visualization of latent fingerprints on unfired brass cartridges has been done by palladium deposition using Auger electron microscopy and scanning electron microscopy [2]. The laser has also been employed to develop prints on smooth boards, wood, some metals, and plastics [3]. Latent fingerprint detection, Received March 24, 2005; accepted April 27, Department of Forensic Science, Punjabi University, Patiala India 2 Department of Chemistry, SGTB Khalsa College, New Delhi, India 374 / 56 (3), 2006

2 specifically on wooden surfaces, has also been undertaken using chemical methods [4]. Semiporous surfaces have also been dealt with quite comprehensively, with major research being conducted on polymer bank notes, laboratory gloves, expanded polystyrene, and waxed paper [5]. Various porous surfaces on which latent print development has been done are paper, cardboard, and raw (untreated) wood, using ninhydrin [6], DFO [7], physical developer [8], iodine, and dimethylaminocinnamaldehyde [9]. One type of surface that a crime scene investigator may come across and ignore is that of fruits and vegetables. Half-eaten fruits are commonly found at the scene of a crime and thus the potential for latent fingerprints is present. However, few reports have been written on this topic. Grahm [10], using radiography, reported the development of latent fingerprints on the surfaces of various fruits. Theys et al. [11] attempted to develop latent fingerprints on an onion, but the attempts (using vacuum metal deposition) were unsuccessful. Fruits and vegetables are biological material that are subject to deterioration. This deterioration is dependant on the ripeness of the fruit as well as on environmental and storage conditions (e.g., temperature and humidity). Thus, fruits present an unusual surface and may need a different treatment. Keeping these factors in mind, a time study was attempted to develop latent fingerprints on fruit and vegetable skins. Materials and Methods In this study, four fruits (apple, guava, banana, orange) and three vegetables (tomato, onion, potato) were selected as surfaces for testing. Samples were collected in fresh form from the retail market. Fingerprints were impressed in the normal manner in which someone would hold the sample. Prior to the handling, the hands were subjected to normal actions, which included the touching of the fingers to the face (the hands were not washed nor wiped with a towel). Sample prints were collected from five people working in the laboratory. There was no attempt to fix the prints. The prints were developed on the same day and thereafter on days 2, 3, and 7. The fruits and vegetables that had been impressed with latents were kept uncovered in a room to imitate actual field conditions as far as possible. The temperature during the experimental work varied from 15 to 25 ºC, with approximately 60% relative humidity. 56 (3), 2006 \ 375

3 Development of Latent Fingerprints (a) (b) Powder Method - Two types of powders were used: activated charcoal powder (Ranbaxy Laboratories, India) and lightning gray powder (Ideal Scientific Concern, India). The powders were applied with feather brushes. After the development of the latent fingerprints, the excess powder was removed with a gentle blow of air. Powdering is the most commonly used technique for smooth nonporous surfaces. It is based on the principle of differential adhesion of powder on fingerprint deposits [12]. This technique is simple and inexpensive and provides instantaneous results that are ready to be lifted. Iodine Fuming Method - Samples were exposed to iodine vapors by hanging in an enclosed glass chamber. The exposure time was determined by a visual assessment of the fingerprint development [13]. There was no attempt to fix the developed fingerprints. Iodine fuming is one of the oldest known techniques for the development of latent fingerprints. Iodine is absorbed by the sebaceous materials to produce slightly brownish prints [13]. Recording of Fingerprints The developed prints (powdered and iodine) were then lifted by clear adhesive tape, affixed to a clean white sheet of paper, and scanned using a flat bed scanner (600 dots per inch, gray scale). The scanned prints were stored in a lossy compression format (i.e., JPEG) to facilitate better storage. Results Table 1 summarizes the results and indicates the quality of prints after their development on the different fruit and vegetable surfaces. The apple had the best surface for the development of latent fingerprints. The surface of the apple is smooth and the shelf life is longer, thus facilitating the development of latent prints on the apple s surface for a longer period of time. The apple s surface responded well to the gray powder treatment, but a better contrast was observed with the black powder treatment. The iodine fuming method provided prints that were clear in some areas, but the developed prints were not of good contrast in comparison to the ones developed with the black or gray powder (Figure 1). 376 / 56 (3), 2006

4 Sample Number Samples Day Black Powder Gray Powder Iodine Fuming 1. Apple One Two Three Seven Banana One Two Three Seven Guava One Two Three Seven Orange One Two Three Seven Tomato One Two Three Seven Onion One Two Three Seven Potato One Result Key: Two Three Seven (+++) very clear development (i.e., all the ridges can be seen clearly) (++) clear developments (i.e., some areas were smudged) (+) poor development (-) Results inconclusive Table 1 Quality of the developed latent fingerprints on fruit and vegetable surfaces. 56 (3), 2006 \ 377

5 The prints from the banana s surface were of the same quality as those of the apple when the banana was one and two days old, but by the third day, because of the banana s soft nature and moisture-containing surface, the prints were smudged, and lifting with the tape became difficult. The gray powder treatment was best for achieving proper contrast in this case. The developing conditions gradually worsened because of the shorter shelf life. On the first day, both the black powder and the silver powder produced equally good results on the guava. However, with the passage of time, the surface shrank, causing difficulty for the development as well as lifting of the developed prints. In this case also, gray powder was more suitable (Figure 2). The uneven surface of the orange posed a problem: Though development of the latent prints by all the methods yielded good results and produced clear visibility, during the lifting of the prints, the uneven surface appeared as dots in the lifts. (Closeup photography of the latent print on the orange can be used to eliminate or overcome the problem of the uneven surface.) Even so, the ridges were quite clear to the extent of the identification. Black and gray powders produced good results for two days, but the iodine fuming did not work; none of the results were satisfactory. On the 7th day, the surface of the orange completely degraded, and none of the methods were satisfactory. The tomato has a very smooth and glossy surface and, because of its color, the black powder gave very good contrast (Figure 3). There was less clarity of the prints developed with the gray powder (because of the obvious reason of contrast), and the iodine fuming method produced average contrast. Development of fingerprints on the onion s surface was achieved with the help of powders, but the proper contrast was lacking with the iodine treatment. Development of fingerprints on the potato s surface was achieved with black powder (Figure 4). The iodine fuming method did not provide good results. Conclusions Fruits and vegetables with latent fingerprints may be encountered at crime scenes and should not be discounted as possible sources for processing. Black powder proved to be a suitable method for recovering prints. Iodine fuming was not a satisfactory method. The quality of developed prints was also affected by the condition of the fruits and vegetables. 378 / 56 (3), 2006

6 Figure 1 Iodine fuming lift from the apple, day one. Figure 2 Gray powder lift on guava, day one. Figure 3 Black powder lift from tomato, day three. Figure 4 Black powder lift on potato, day one. 56 (3), 2006 \ 379

7 For further information, please contact: Dr. O. P. Jasuja Department of Forensic Science Punjabi University Patiala India References 1. Connor, C. M. Development of Latent Fingerprints on a Non-porous Surface, Using Standard Brushing Method for Powders: Second Collaborative Study. J. Assoc. Off. Anal. Chem. 1975, 58 (1), Migron, Y.; Mandler, D. Development of Latent Fingerprints on Unfired Cartridges by Palladium Deposition: A Surface Study. J. For. Sci. 1997, 42 (6), Burt, J. A.; Menzel, E. R. Laser Detection of Latent Fingerprints: Difficult Surfaces. J. For. Sci. 1985, 30 (2), Cihangiroglu, B.; Saygi, S. Developing the Latent Prints on Paper and Wooden Surfaces with Physical and Chemical Methods. For. Sci. Int. 2003, 136 (1) supplement, pp University of Technology Sydney: Centre for Forensic Science website. Announcement for final PhD seminar: Naomi Jones. Metal Deposition Techniques for the Detection and Enhancement of Latent Fingerprints on Semi-Porous Surfaces. accessed February 24, Kent, T., Ed. Manual of Fingerprint Development Techniques, 2nd ed.; Home Office, Police Scientific Research Development Branch: Sandridge, UK, Pounds, C. A.; Griggs, R.; Mongkolaussavaratana, T. The Use of 1,8-Diazafluoren-9-one (DFO) for the Fluorescent Detection of Latent Fingerprints on Paper: A Preliminary Evaluation. J. For. Sci. 1990, 35 (1), Phillips, C. E.; Cole, D. O.; Jones, G. W. Physical Developer: A Practical and Productive Latent Print Developer. J. For. Ident. 1990, 40 (3), Sasson, Y.; Almog, J. Chemical Reagents for the Development of Latent Fingerprints, Scope and Limitations and Reagent 4-dimethylaminocinnamadehyde. J. For. Sci. 1978, 23 (4), / 56 (3), 2006

8 10. Graham, D. Routine Fingerprint Investigation. In The Use of X-ray Techniques in Forensic Investigations. Churchill Livingstone: London, 1973; pp Theys, P.; Turgis,Y.; Lepareux, A.; Chevet, G.; Ceccealdi, F. New Technique for Bringing Out Latent Fingerprints on Paper: Vacuum Metallization. Int. Crim. Pol. Review 1968, 217, Wilshire, B. Advances in Fingerprint Detection. Endeavour 1996, 20 (1), Champod, C.; Len nard, C. J.; Magot, P.; Stoilivic, M. Miscellaneous Techniques for Detection of Latent Finger prints. In Fingerprints and Other Ridge Skin Impressions. CRC Press: Boca Raton, FL, 2004; pp (3), 2006 \ 381