Recovery of latent fingermarks on food

Small particle reagent (SPR) technique is a method used for detecting latent fingerprints on wet, non-porous surfaces by suspending nanoparticles in a reagent that binds with fatty acid residues on fingerprints. The small particle reagent technique is particularly effective for detecting latent fingerprints on evidence that has been submerged underwater for prolonged periods. However, due to its reliance on imported reagents, SPR is often expensive and involves a lengthy waiting period. Consequently, many researchers have attempted to develop SPR formulations using easily obtainable, cost-effective, and safe chemicals. In this study, we prepared two new SPR formulations containing zinc oxide nanoparticles mixed with diethylene glycol monoethyl ether. Both formulations used a surfactant composed of two types (sodium tetradecyl sulfate and Tergitol NP-9) for the development of latent fingerprints on wet surfaces. Latent fingerprints were deposited on four different non-porous surfaces, including stainless-steel spoons, glass slides, aluminum foil, and plastic slides. These surfaces were immersed in tap water for 1, 3, 7, 14 and 30 days. The resulting latent fingerprints were analyzed using the Mini Automated Fingerprint Identification System and were shown to produce clear, sharp, and detailed fingerprints on the non-porous surfaces. The best results were found on the surfaces of stainless-steel spoons with both formulations, where minutiae were detectable at more than 40 points even after the surfaces had been immersed in water for up to 30 days. This study provides forensic scientists and crime scene investigators with a faster and safer method for developing latent fingerprints using non-hazardous materials, which could serve as an alternative to conventional formulations.

BackgroundFingermarks can be found both in indoor and outdoor crime scenes. The latter could be subjected to various types of environmental insults. In many cases, criminals try to dispose of or conceal the evidence in several ways, such as throwing in the waterways or burying in the soil to avoid detection from the law enforcement agencies. Thus, crime scene investigators often face challenges to detect and develop latent fingermarks in such environments. This study aimed to investigate the persistence and ageing of latent fingermarks in a burial environment for particular periods. To date, there is a limited study that attempted to investigate the survivability of fingermarks in a burial environment.MethodologyThe experiment was carried out in two settings: preliminary and main experiments. A preliminary experiment was conducted indoor to determine the most effective chemical for fingermark development on buried metal substrates. Five different chemicals were employed to develop the latent fingermarks, namely fingermark powder dusting, small particle reagent (SPR), Sudan black, oil red O, and crystal violet. The main experiment was carried out to simulate the realistic situation in which the metal substrates bearing latent fingermarks were buried in the soil within 2 months period. In both experiments, the substrates were buried in peat soil at a depth of 10 cm from the surface.ResultsThe results demonstrated that latent fingermarks could be effectively recovered after being buried in the soil up to 8 weeks using Sudan black. The position of the substrates whether underlying in “face up” or “face down” orientations when buried had also influenced the quality of the developed fingermarks. Fingermarks buried in the “face up” position demonstrated better quality and more ridge details as compared to those buried in the “face down” position. Secondary fingermarks were also observed in this study and found to be useful for identification and must be taken into consideration when developing fingermarks on buried items in forensic cases.ConclusionThe development of fingermarks recovered from burial environments is feasible as excellent ridge characteristics can still be identified. Hence, any evidence recovered from burial sites should be examined for fingermarks and cannot be discounted.

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.

The latent fingerprint may be found on items which have been accidentally or deliberately wetted. One of the most effective application techniques for developing latent prints on wet non-porous surfaces is small particle reagent (SPR). SPR based on zinc carbonate and mixed with natural dyes (curcumin and anthocyanin) and commercial liquid detergent. Immersed the latent fingerprints into clean water and dirty water for 30 days, i.e. stainless, mirror and plastic slide. Three surfaces were taken out and sprayed with SPR formulations everyday. In the present experimental study the best results were given by stainless surface followed by glass and plastic, respectively.

Small particle reagents: Development of fluorescent variants

Development of latent fingerprints on wet non-porous surfaces with SPR based on basic fuchsin dye

Development of latent fingermarks on surfaces submerged in water: Optimization studies for phase transfer catalyst (PTC) based reagents

In the field of practical forensic activities due attention is not given to the examination of human skin cover traces left on the outer shell of plant fruits both while conducting an incident site inspection and during forensic examination. A few scattered publications available predominantly in the foreign forensic literature provide recommendations towards examination of such traces through the use of both conventional physic, physical-chemical methods and technical means for detection and fixation of latent hand traces and non-standard ones (applied to food colourant powders, corn meal powders, cocoa powder etc.). In the course of experimental works latent hand traces were formed on the most commonly encountered fruits and vegetables having different retention times (tomatoes, apples, potatoes, onions, pumpkins, bananas). To detect and fix them there were applied such technical and forensic means as fingerprint powders (magnetic and non-magnetic powders, including luminescent ones), dispersive medium of dark color (analogue of commercial product - small particle reagent), cyanoacrylates. The authors analyzed the obtained experimental material and submitted recommendations towards the detection of hand traces formed on the outer shell of plant fruits.

Introduction: Recovery of evidence such as murder weapons in waterways has been commonly reported. However, visualising latent fingerprints on the immersed substrates may prove challenging due to its obliteration by physicochemical parameters (e.g. pH, temperature, salinity) as well as the mechanical effect of water. Although the use of Small Particle Reagent (SPR) for visualising latent fingerprints on wet non-porous substrates has been suggested, it contains molybdenum and titanium that are toxic, and their utilisation must be reduced. Furthermore, no study verifies the chemical and/or physical interaction between SPR and the lipid constituents of wet latent fingerprints that leads to the visualisation of ridge details. Methods: The SPR and newly developed nanobio based reagent (NBR) i.e. Candida rugosa lipase-multiwalled carbon nanotubes (CRL-MWCNTs) were used for visualising latent fingerprints on glass slides immersed in water with salinitylevels representing those of estuary and swimming pool for up to 15 days. Results: It was observed that the quality of the visualised fingerprints using NBR was comparable with that of SPR. Characterisations via instrument and bioinformatics analyses have also verified the incorporation of CRL onto MWCNTs and the chemical interaction between NBR and lipid constituents of wet latent fingerprints. Conclusions: Therefore, the newly developed NBR may prove a promising relatively greener alternative for substituting SPR for visualising latent fingerprints on glass slides immersed in different levels of water salinity.

This study evaluates the effectiveness of a small particle reagent (SPR) formulation based on Phloxine B dye for developing latent fingerprints on submerged non-porous surfaces. The primary objectives were to assess the formulation’s ability to produce fingerprints over time and determine its shelf life. The reagent was tested on three non-porous surfaces—glass, aluminium foil, and plastic transparency sheets—submerged in tap water for a duration of 30 days. Additionally, the study extended to evaluate the reagent’s performance on surfaces submerged in sewage water. The results demonstrated that the formulation successfully developed high quality identifiable fingerprints over a period of 27 days on glass, 29 days on transparency sheets, and 24 days on aluminium foil, after submersion in tap water. In the case of surfaces submerged in sewage water for 84 h, metal produced higher-quality and more durable prints compared to glass and plastic. On average, the Phloxine B-based SPR formulation demonstrated a shelf life of about 60 days. This Phloxine B-based SPR composition offers a non-toxic, cost-effective, and highly efficient approach, in the recovery of latent fingerprints from submerged non-porous surfaces.

Second level dactyloscopic markants (minutiae) are irregularities in the course of the friction ridge skin used for personal identification because of their high variability. Individual uniqueness is affected by the high number of minutiae and their random distribution within the friction ridge skin. The combination of various environmental factors, e.g., snow, soil environment, and direct sunlight, can affect the quality of fingerprints. The aim of this study was to analyze the influence of snow under two different conditions (natural snowfall and immersion in the snow) within various time intervals on fingerprints. A total of 265 groomed latent distal fingerprints were taken from a Caucasian male from Slovakia. Latent fingerprints were taken only from one participant, as the composition of sweat, i.e., the sweat-fat substance, varies from person to person, which could influence the results. Subsequently, obtained latent fingerprints were developed using small particle reagent. We evaluated the decrease in the number of minutiae on latent fingerprints exposed to the destructive influence of snow. The results confirmed that snow has a significant effect on the quality of latent fingerprints, as a decrease in the average number of minutiae on latent prints was observed after only 2 h of exposure to snow conditions. After snow exposure, usable fingerprints for identification decreased, whilst non-usable ones increased, with 53.33% of non-usable fingerprints resulting from natural snowfall exposure. After exposure of latent fingerprints to snow immersion, 98.13% of non-usable fingerprints were found. The results can help improving personal identification efficiency.Key Points Fingerprints exposed to various environmental factors are recommended to be evaluated.Visual quality of latent prints decreases with the length of exposure to snow conditions.The average number of minutiae decreases significantly after the influence of snow conditions.Snowfall has a less negative influence on the average number of minutiae than forcible immersion.Latent fingerprints exposed to snowfall have better identification potential.

BackgroundFingermarks are one of the oldest, reliable, and universally accepted evidence found on the crime scene. They can be used to link suspect with scene of crime and weapon of offence. Fingermarks are frequently used to investigate criminal cases and identify missing persons and criminals.Main textConventional methods such as cyanoacrylate fuming, iodine fuming, ninhydrin, silver nitrate, small particle reagent, and powder dusting are routinely used to detect and develop latent fingermarks on various surfaces of forensic importance. However, these methods suffer several limitations including poor contrast, low sensitivity, background interference, and low specificity. To overcome these limitations, nowadays, nanoparticles have gained importance in the development of latent fingermarks. In this review, we focus on the carbon dots (CD's) nanomaterial for the development of latent fingermarks. CD’s have superior fluorescence performance, color tuneability, and low synthesis cost and are non-toxic. The color and intensity of luminescence of CD's depend on its morphology and synthesis method. CD's can be used either in solid or solution form to develop latent fingermarks on the various porous and nonporous surfaces.ConclusionCD’s are potentially a good candidate to develop latent fingermarks on wide range of porous and nonporous items of forensic importance. The fingerprints developed with CD’s show excellent contrast and resolution. Their small size, biocompatibility, facile and low-cost synthesis, and color tuneability can be successfully utilized to overcome the limitations of the conventional methods.

Fingerprints are a useful source of evidence in establishing the identity of the person and hold large importance in crime scene investigations. A diverse range of physical and chemical methods are available for the development of latent fingerprints, but limited work is done on detection of prints from wet non-porous surfaces. The study aimed at developing a novel method for identification of latent fingerprints from such a type of surface. Small Particle Reagent was prepared using non-toxic chemicals and was proven to be effective in detecting latent fingerprints on Aluminum Foil. Fluorescent component, Basic Yellow-40 dye was used in the formulation. The Shelf life of the SPR solution was also considered an important factor in the study and was found to be 25 days.

Small particle reagent (SPR) method for detection of latent fingermarks: A review

Fingerprints are well known to be an important aspect of a criminal investigation due to their ability to identify an individual. Today, there are numerous methods to enhancing latent fingerprints. Some of these methods were performed on the adhesive side of various types of tapes in order to determine which method produced the greatest print development. The methods used were: dusting using various powders, small particle reagent (SPR), crystal violet, and cyanoacrylate fuming. Only two of the techniques used preformed well across a majority of the tapes. Even though all of the techniques did not preform well on all of the tapes they gave some valuable information that could be used to better results. The most successful techniques were the cyanoacrylate fuming and crystal violet. Both of these methods developed prints that were detailed with superior contrast compared to the other methods performed. Even though both techniques were superior, the cyanoacrylate fuming developed the higher quality prints. The cyanoacrylate fuming performed greatest when fumed with water for humidity followed by a dusting of fingerprint powder. These two methods were both simple to perform and were completed within a timely manner. Overall, the cyanoacrylate fuming could be preformed more efficiently because multiple prints could be developed at one time.