Development of latent fingerprints on non-porous surfaces recovered from fresh and sea water

Abstract

BackgroundCriminal offenders have a fundamental goal not to leave any traces at the crime scene. Some may suppose that items recovered underwater will have no forensic value, therefore, they try to destroy the traces by throwing items in water. These traces are subjected to the destructive environmental effects. This can represent a challenge for forensic experts investigating fingerprints.MethodsThe present study was conducted to determine the optimal method for latent fingerprints development on dry non-porous surfaces submerged in aquatic environments at different time interval. The quality of the developed fingerprints depending on the used method was assessed. In addition, two factors were analyzed in this study; the effects of the nature of aquatic environment and the length of submerged time. Therefore, latent fingerprints were deposited on metallic, plastic and glass objects and submerged in fresh and sea water for 1, 2, and 10 days. After recovery, the items were processed by black powder, small particle reagent and cyanoacrylate fuming and the prints were examined. Each print was evaluated according to fingerprint quality assessment scale.ResultsCyanoacrylate developed latent prints found to have the highest mean visibility score after submersion in fresh and sea water for 1, 2 and 10 days. Mean visibility score of prints developed showed significant decline after 10 days of submersion. Prints submerged in fresh water showed significantly higher mean visibility score than those submerged in sea water using various methods of development and in all time intervals.ConclusionThe study demonstrated that it is possible to recover latent prints submerged in water on different studied dry non porous surfaces with the best visualization method using cyanoacrylate either in fresh or sea water. The duration of submersion affects the quality of fingerprints developed; the longer the duration, the worse the quality is. In addition, this study has revealed that the exposure to high salinity i.e. sea water has more damaging influence on the quality of detected fingerprints.It is concluded that any piece of evidence recovered from underwater should be tested for prints, no matter the amount of time spent beneath the surface.

Relevant visualization technologies for latent fingerprints on wet objects and its challenges: a review

“…On top of that, the consistent inadequate quality of fingerprints recovered from immersed evidence continues to pose an uphill challenge, presumably due to the duration of immersion (Trapecar 2012;Rohatgi et al 2015;Rohatgi and Kapoor 2016) as well as different types of water (Rohatgi et al 2015). Such observation was also supported by Madkour et al (2017) whereby the authors reported on relatively poor performance of SPR in visualizing latent fingerprints on glass, metal and plastic surfaces, particularly after exposure to sea and lake waters in different aquaria for more than 24 h.…”

A review of fingerprint recovery within an arson crime scene

“…Madkour 45 found the Cyanoacrylate fuming technique to be the most suitable technique for items submerged in fresh and salt water for up to 10 days. 45 This disputes many other sources stating this technique cannot be used if the item have been wet. The longer the time before a fingerprint is treated, the higher the impact of degradation.…”

“…The longer the time before a fingerprint is treated, the higher the impact of degradation. 45 The components enhanced in cases regarding water submersion may be the components that are changed by the heat and may not be detectable after both exposures. For example, salt is able to withstand intense heat and is believed to be the most durable fingerprint component, however, it is water soluble so may be washed away if exposed to water during the extinguishing efforts.…”

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“…44 This is useful to be aware of as the fingerprint may have not been initially damaged by the heat, however, may possibly be damaged if submerged in water until the investigation team attend the scene. Madkour 45 found the Cyanoacrylate fuming technique to be the most suitable technique for items submerged in fresh and salt water for up to 10 days. 45 This disputes many other sources stating this technique cannot be used if the item have been wet.…”

“…Water with a higher salinity value than fresh water has a more detrimental effect on the quality of the fingerprint obtained. 45 Some fingerprints will emit a weak luminescence. The source of this is unknown and believed to be from contamination to the natural eccrine secretion residues.…”