Development Of Latent Fingerprints Research Articles

Exploring sustainable forensics: silica nanoparticle powder derived from rice husk waste for aged fingermark development and the chemistry of surface interactions

BackgroundPowder-based fingermark ridge visibility enhancement is a common technique employed in crime scenes due to ease of application and robustness of the application method. Pigmented powders created a contrast between the surfaces and developed ridgelines and are generally metals or metal oxides based. Previous research showed the successful development of fresh latent fingermarks using rice husk-derived silica nanoparticles on various surfaces. Nevertheless, there has been less previous evidence for the efficiency of the silica nanoparticle powder on aged fingermark development. Therefore, the aim here is to investigate the efficacy of the powder on aged fingermarks relative to commercial formulation to gauge the feasibility of having naturally derived powder as a possible alternative for field application and commercialisation.ResultsRigorous testing over a range of non- and semi-porous surfaces at varied ageing conditions revealed a minimal disparity in the performance of both powders on most surfaces. Still, silica nanoparticles exhibited superiority in terms of selectivity on silica-based surfaces. Close up analysis of developed fingermarks using electron microscope exposed clear demarcation between fingermark ridges and valleys using silica nanoparticles.ConclusionsFindings revealed that the interaction chemistry between powder particles and surface material either enhances or lowers the fingermark development capacity depending on the type of surface tested.

Synthesis of phenol formaldehyde resin (PFR) based fluorescence resonance energy transfer (FRET) composites for double channel detection of latent fingerprints.

A reversible two-channel fluorescent nanocomposite with fluorescence resonance energy transfer (FRET) effect was designed for the development, analysis, and characterization of latent fingerprints (LFPs). For the construction of the FRET probe, a core of mesoporous silicas (MSNs) were used to encapsulate the organic dye rhodamine 6G (RhD-6) as an acceptor, while green-emitting monodisperse phenolic resin nanoparticles (PFR NPs) were selected as a donor. The up-conversion material (UC) of NaYF4:Yb,Er was synthesized using a simple hydrothermal method, and the MSNs-RhD-6/PFR (PRM) was electrostatically adsorbed onto the UC nanoparticles using a layer-by-layer method to obtain MSNs-RhD-6/PFR-UC (PMU). Compared to ordinary single-channel materials, PMU can be excited by different light sources (365 nm UV/980 nm laser) and its fluorescence can be reversibly switched between yellow and green, demonstrating excellent light reversibility. The PMU composites were successfully used to visualize and detect LFPs on various substrate surfaces using a simple powder coating method. Due to the existing FRET effect and dual-channel characteristics, this composite material displays excellent contrast, outperforming commercially available products for wider applicability. Even on complex backgrounds and after aging or washing treatments, it still clearly recognizes fingerprints in first-, second-, and third-level details, showing its great potential in latent fingerprint detection.

The effectiveness of natural indigo/kaolinite composite powder in the development of latent fingermarks

BackgroundComposites are materials that have multiple phases and have attracted much attention as they are able to improve physical and chemical properties of an isolated material. In this sense, these composites are commonly used as key components for two purposes: coloring and improving the operational properties; besides that, they have alternative synthesis routes that respect the principles of green chemistry. Thus, this reports the development of a new composite using natural products, indigo and kaolinite, for application in papilloscopy as a new nontoxic fingermark developer.ResultsThe composite was obtained via green procedures and was characterized by spectroscopic and chromatographic techniques. Thus, to investigate the potential of the material as a fingermark developer, different techniques were applied such as depletion, aging, comparison with commercial powder, and development of latent fingermarks on different surfaces. Tests revealed that the composite presented good contrast and adhesion with the latent fingermarks, even after 15 days of deposition.ConclusionsThis study presents a natural indigo/kaolinite composite powder that showed similar or higher efficiency when compared to the commercial fingerprint powder and was able to develop identifiable natural and sebaceous fingermarks.Key points• A composite was formed from eco-friendly materials.• The composite formation follows the concepts of green chemistry and low cost.•The composite was applied as a latent fingermark developer.

Non-destructive and simultaneous development and enhancement of latent fingerprints on stainless steel based on the electrochromic effect of electrodeposited manganese oxides

Latent fingerprints, as one of the most frequently encountered traces in crime scene investigation and also one of the largest sources of forensic evidence, can play a critical role in determining the identity of a person who may be involved in a crime. Due to the invisible characteristic of latent fingerprints, exploring efficient techniques to visualize them (especially the ones resided on metallic surfaces) while retain the biological and chemical information (e.g., touch DNA) has become a multidisciplinary research focus. Herein we reported a new and highly sensitive electrochemical interfacial strategy of simultaneously developing and enhancing latent fingerprints on stainless steel based on synchronous electrodeposition and electrochromism of manganese oxides in a neutral aqueous electrolyte. By utilizing a specially designed device for electrochemical testing and image capture, a series of electrochemical measurements, physical characterization and image analysis have been applied to evaluate the feasibility, development accuracy and enhancement efficacy of the proposed electrochemical system. The qualitative and quantitative analysis on the in situ and ex situ fingerprint images indicates that the three levels of fingerprint features can be precisely developed and effectively enhanced. Forensic DNA typing has also been performed to reveal actual impact of the proposed electrochemical system on subsequent analysis of touch DNA in fingerprint residues. The ratio of detected loci after electrochemical treatment reaches up to 98.5 %, showing non-destructive nature of this fingerprint development and enhancement technique.

Optimization of crystal violet technique for enhanced fingerprint detection on various surfaces.

The crystal violet (CV) staining technique represents a prevalent approach for the development of latent fingerprints, especially on adhesive tape surfaces. Nevertheless, the technique necessitates intricate formulations to augment its performance. In this investigation, an optimized CV staining protocol was developed, characterized by the absence of residual dye on the target substrates and the capability of facilitating fingerprint visualization under ambient light conditions. Four donors, comprising two males and two females, deposited natural fingerprints on various substrates, including glass microscope slides, aluminum foil, and 115 g glossy coated paper, without any specific guidelines. Fingerprints developed using cyanoacrylate fuming served as benchmarks and were contrasted with those generated through alternative methods: CV, ardrox, rhodamine 6G, powdering, and the optimized CV staining protocol. The fingerprint development experiment was replicated at seven distinct time intervals, encompassing 1 day, 1 week, 1, 3, 6, 9, and 12 months, resulting in a dataset of 420 fingerprints. The evaluation of fingerprint identifiability employed a scoring system established by the Home Office Centre for Applied Science and Technology. The results indicated that the optimized CV staining technique demonstrated superior performance, boasting a 92.9% rate of identifiable fingerprint development in contrast to other employed methodologies. Consequently, this optimized CV staining approach is recommended as an efficient, rapid, and straightforward critical dyeing method, applicable to a wide array of substrates in forensic investigations.

A Review of Latent Fingerprint Developed Powder from using Natural Materials

The fingerprint development technique is one of the oldest methods used in forensic science and is a common method of identifying perpetrators. [1] Different powder methods have been accounted for the development of latent fingerprints on various surfaces in the literature, such as lead, titanium oxide, Rhodamine B dye etc., all powders mentioned had been used for the development of latent fingerprints. Some of these methods using powders when exposed to humans, may lead to health problems, and also these methods are expensive in nature [2]. Various fingerprint powder preparations used for fingerprints have a color or contrast and a sticky material for good adhesion [3]. The goal of this review is to compile the research works done by various experts to identify commonly available, everyday materials as fingerprint powders such materials from various categories such as food powders, plant materials, minerals, cosmetics, carbon-based materials, and miscellaneous powders [1]. The powder method is a quick and easy approach to the development of latent fingerprints on porous and nonporous surface [4]. proposing a new powder method, which is simple, nontoxic to human health, cheap in nature, and as well can be utilized for the development of latent fingerprints on various contrast surfaces [2].

Development of Latent Fingerprints on Various Surfaces- A Review

Development of Latent Fingerprints on Various Surfaces- A Review

Potential of Y2Sn2O7:Eu3+, Dy3+ Inorganic Nanophosphors in Latent Fingermark Detection

In this work, we investigated the potential of Eu3+/Dy3+-codoped Y2Sn2O7 fluorescent nanophosphors to visualize latent fingermarks. We prepared these nanophosphors with various doping concentrations by the conventional coprecipitation reaction. The crystal structure, morphology, luminescence properties, and energy transfer mechanisms were studied. The crystalline phase was characterized by X-ray diffraction and crystal structure refinement using the Rietveld method. XRD measurements showed that the samples crystallized in the pure single pyrochlore phase with few more peaks originated from secondary phases and impurities generated during phosphor production, and that Eu3+ ions occupied D3d symmetry sites. The average crystallite size after mechanical grinding was less than 100 nm for all compositions. The optical characterization showed that, when excited under 532 nm, the Eu3+/Dy3+-codoped Y2Sn2O7 samples’ main intense emission peaks were located at 580–707 nm, corresponding to the 5D0→7Fj (j = l, 2, 3, and 4) transitions of europium. In fact, the 5D0→7F2 hypersensitive transition is strongly dependent on the local environment and was quite weak in Eu3+:Y2Sn2O7 at low Eu3+ doping levels. We found that the presence of Dy3+ as a codopant permitted enhancing the emission from this transition. The calculated PL CIE coordinates for the synthesized nanophosphors were very close to those of the reddish-orange region and only slightly dependent on the doping level. Various surfaces, including difficult ones (wood and ceramic), were successfully tested for latent fingerprint development with the prepared Eu3+/Dy3+-codoped Y2Sn2O7 fluorescent nanophosphor powder. Thanks to the high contrast obtained, fingerprint ridge patterns at all three levels were highlighted: core (level 1) islands, bifurcation, and enclosure (level 2), and even sweat pores (level 3).

Ultra-bright green emitting Sr2MgSi2O7:Tb3+ nanophosphors: unveiling multi-security applications in anti-counterfeiting, flexible films, optical thermometry and latent fingerprint visualization

In this study, we synthesized facile green-emitting Sr2MgSi2O7:Tb3+ (1–11 mol %) nanophosphors (SMSO:Tb3+ NPs) using a solid-state reaction method. Characterization through X-ray diffraction (XRD) revealed a tetragonal crystal structure in the as-synthesized SMSO:Tb3+ NPs. Crystallographic data obtained from Rietveld refinements identified the specific sites of Tb3+ ions in the host material. Chemical and photo-luminescent properties are explored using X-ray photo-electron spectroscopy (XPS) and Photoluminescence (PL) spectroscopy, respectively. The NPs exhibited vibrant green emission at 547 nm, attributed to the Tb3+ ions' 5D4→7F5 transition, with a high quantum yield of 63.10 %. Optimal doping concentration is determined as 7 mol % (SMSO:7 Tb3+), overcoming concentration quenching primarily due to dipole-dipole (d-d) interaction. Impressively, SMSO:7 Tb3+ NPs demonstrated a correlated colour temperature (CCT) of 5549 K, colour purity (CP) of 91.60 %, and excellent colour stability. These phosphors are effectively applied in latent fingerprints (LFPs) development, revealing distinct ridge features useful for personal identification. Additionally, SMSO:7 Tb3+ NPs, combined with soluble PVA, are used to create a transparent anti-counterfeiting (AC) film, exhibiting intense green emission under UV 365 nm light. Notably, the film flexibility, durability, and foldability enhance its applicability in AC techniques. This study showcases SMSO:Tb3+ NPs as versatile luminous platforms with applications in flexible displays, high-colour quality lighting, fingerprint (FP) visualization, and anti-counterfeiting.

Multi‐Purpose Fluorescent Powder: Development of Latent Fingerprints and Glove Prints

AbstractA novel hydroxy benzothiazole based yellow fluorescent powder (labelled as 2‐SiO2) was prepared by adsorption of 2 on silica (4 % w/w) for visualization of latent fingerprints (LFPs) and glove prints using powder dusting method. The solid‐state spectrum of 2‐SiO2 shows emission peak at 550 nm with CIE‐1931 coordinates ( ) of 0.42, 0.50 and yellow colour purity is 58.6 %. The high fluorescence of 2 in the solid‐state could be attributed to AIE+ESIPT features. Due to high fluorescence of 2‐SiO2 (4 % w/w) powder, fluorescence imaging of LFPs on a variety of porous and non‐porous substrates including glove prints, up to levels 1–3, without any post‐treatment has been achieved. The 2‐SiO2 showed strong interaction with D‐Glucose, urea and lactate components present in sweat. The practical applications of 2‐SiO2 powder have been demonstrated by analysis of LFPs, development of LFPs at different temperatures; aged, stained fingerprints and preservation of developed fingerprints for documentation purposes.

Role of doped ZnO variants for the development of latent fingerprint

Here we are presenting a promising approach for the green synthesis of zinc oxide (ZnO) nanomaterials by using lemon grass with minimal environmental impact. The fabricated zinc oxide (ZnO) doped with different dyes ranging from 25 −100 nm were applied to read the minutiae points of finger prints that can lead for person identification. In this model project, we doped different dyes on ZnO and used for the development of latent finger prints on different surfaces and at time duration (1 h to 24 h). The linkage between nanomaterials and fingerprint residues is among oxide group and amine group. We presented that these designed materials have the ability to develop fingerprints on variety of substrates. We displayed that with the passing of time the chroma index and intensity reduce but still at 24 h we can read the minutiae details. This research opens a new era to enhance and quantifying contrast between surface and applied material.

A strategy for the enhanced development of latent fingermarks with minimally destructive to DNA based on fluorescence Eu-Tb metal–organic framework

Fingermarks identification have always been the most effective and reliable way for individuals determination among the forensic science. The fingermarks at the scene of the case as the valuable physical evidence to analyze the trajectory of criminal behavior and portray the characteristics of the suspect play an irreplaceable role in the process of investigation. To reach its pivotal biometric individualization, the luminescent metal–organic framework (Eu@Tb-LL) was prepared via a simple optimized solvothermal method for visualizing the latent fingermarks with minimally destructive to DNA in this work. Eu@Tb-LL exhibited ideal optical stability and fluorescence intensity at the wavelength of 530 and 620 nm during revealing latent fingermarks. Meanwhile, Eu@Tb-LL is more effective than indandione (commonly used in the site investigation) in revealing aged fingermarks. More significantly, the Eu@Tb-LL superimposed on commercial manifestation reagents (Hfb) enhanced the effect of Hfb for revealing blood latent fingermarks on the non-porous objects. In addition, the STR testing results performed after the visualization process proved the Eu@Tb-LL was minimally destructive to DNA with a confidence interval of 95 %, exhibiting promising prospects for practical criminal investigation applications.

Endowing an amphiphilic aggregation-induced emission molecule with turn-on fluorescence in both latent fingerprints development and antibiotics detection

The water-soluble aggregation-induced emission (AIE) molecule is desirable as a turn-on fluorescence probe, but it is challenging because most AIE-based molecules are lipophilic and can emit strong fluorescence in water. To address the problem, tetraphenylethene (TPE) backbones are decorated with hydrophilic pyridine ethanol-related groups, and a series of novel amphiphilic TPE-based pyridinium salts (denoted as TPE-Py-OH, TPE-2Py-2OH and TPE-4Py-4OH) are synthesized. Encouragingly, TPE-2Py-2OH aqueous solution which is almost non-emissive can be used as a bifunctional turn-on fluorescent probe for developing latent fingerprints (LFPs) and detecting antibiotics. Level 3 details in LFPs are developed via soaking/ spraying method, owing to that AIE phenomenon is activated by the combination of lipophilic part in TPE-2Py-2OH and fatty acid residues in fingerprints. The method is worthy to promote, because it displays the advantages of water solubility, low working concentration, ease of operation, good stability, high safety, high contrast, high sensitivity, and high selectivity. It can also response to penicillin potassium (PNG) with a detection limit of 0.18 μM because the electrostatic interaction between TPE-2Py-2OH and PNG can mainly induce the enhanced fluorescence. This discovery provides a facile approach to design more promising amphiphilic AIE-based turn-on fluorescence probes.

Non-destructive latent fingerprint development and background elimination by Mueller Polarimetry

In this article we have explored the use of Mueller polarimetry for the simultaneous and non-destructive latent fingerprint development and background elimination. This proposal not only expands previously reported uses of the polarization state of light for fingerprint development, but offers some advantages. Samples of a few donors, taken on different heavily back grounded substrates, were measured and processed. Several strategies for background removal were applied. The results are very promising, since the background was successfully erased in all cases and the quality of the developed fingerprints was excellent for most substrates and donors. Considering that the method is non-destructive and that the proposed measurement instrument is inexpensive and portable the method could be tried in real cases with no risk for the evidence. In addition, the success of the procedure for background removal raises the possibility of exploring if it would work for the enhancement of fingerprints developed with other methods.

Unveiling Hidden Prints: Optically stimulated luminescence for latent fingerprint detection

Fluorescent lighting and optical techniques have been widely utilized to enhance the detection of latent fingerprints. However, the development of new techniques is imperative to expand the range of surfaces from which latent fingerprints can be detected. When relying on traditional methods, fingerprint evidence can remain undetected or even disregarded due to insufficient detection and limited detail, especially when dealing with a luminescent background.In this study, we propose the utilization of optically stimulated luminescence (OSL) applied to a Ba2SiO4 matrix, co-doped with Eu2+ and Dy3+, as a powerful method for visualizing latent fingerprints on various surfaces, including thin plastic bags, rigid duct tape, thin aluminum foil, and glass slices. This technique effectively eliminates any luminescent background and significantly enhances optical imaging.This represents the first successful application of OSL in the development of latent fingerprints, thus paving the way for more efficient and effective forensic techniques in the future.

Designing energy transfer-based color-tunable, information-encrypting, luminous hydro-gels, and latent fingerprint detection systems using BaLa2ZnO5:Tb3+, Bi3+ nanophosphors

Synthesizing cost-effective blue-green emitting BaLa2ZnO5:Tb3+, Bi3+ nanophosphors (BLZO:Tb3+, Bi3+ NPs) through an eco-friendly urea-aided combustion method. Thorough examination of phase purity, structure, surface characteristics, and luminescent properties of the resulting products reveals a robust blue-green emission linked to the 5D4 → 7F5 transition of Tb3+ under 365 nm UV excitation, as well as evident energy transfer from Bi3+ to Tb3+ within the co-doped BLZO, discussed in detail. Optimal doping concentrations are determined to be 5 mol% for Tb3+ and 0.3 mol% for Bi3+ in BLZO phosphor, with non-radiative transition mechanisms explaining concentration quenching. BLZO:Tb3+ NPs emits green light, while co-doping with Bi3+ shifted to the blue-green region. The optimized phosphor is employed for latent fingerprint (LFP) development on porous, semi-porous, and non-porous surfaces, with clear visualization under 365 nm UV light. The generated fingerprints (FPs) display level I–III ridge features with exceptional sensitivity, selectivity, and contrast. The luminescent hydro-gels exhibit outstanding photo-stability, chemical stability, and long-term durability, making them ideal for anti-counterfeiting (AC) applications. Furthermore, BLZO:Tb3+, Bi3+ NPs demonstrate the ability to mitigate oxidative stress and thrombosis, evidenced by their DPPH scavenging activity and their capacity to normalize stress indicators in Red Blood Cells (RBC) exposed to NaNO2-induced oxidative stress. These NPs also reduce ADP-induced platelet aggregation. Collectively, these results highlight the effective utilization of the optimized phosphor in display devices, advanced forensics, anti-counterfeiting measures, and biomedical applications.

Potential forensic applications of carbon nanodots

Nanotechnology is a flourishing branch of research due to the incredible properties nanomaterials exhibit over their massive counterparts. Carbon nanodots are the members of the carbon nanoparticle family with prominent properties like hydrophilicity, low toxicity, biocompatibility, increased stability and ease of functionalization. They are excellent replacement to metal based quantum dots which are highly toxic. Carbon nanodots are being used in the fields of medicine, environmental science, drug delivery and forensic science. Applications of carbon nanodots can be seen in bio imaging, bio sensing, cancer diagnosis and treatment, biological activities, solar cells and as photo catalysts. Forensic science is the science behind crime investigation and evidence analysis. Development of novel, rapid, on site testing materials for accurate, specific and sensitive detection of forensic evidences is required for delivery of justice to the victims of crime. Carbon nanodots have shown promising applications in the field of forensic science as well. Use of carbon nanodots as invisible ink for anti-counterfeiting application of currency and security documents and use of these nanomaterials in development of latent fingerprints are some forensic applications. Carbon nanodots based detection of food contaminants, heavy metal poisons, pesticides, illicit drugs and explosives are other forensic applications. Carbon nanodots are showing a future direction in development of on field testing kits for forensic evidences.

Application of Fluorescent Carbon Nanoelectronic Materials in Combining Partial Differential Equations for Fingerprint Development and Its Image Enhancement

Fluorescent developers play a crucial role when dealing with objects with complex patterns or color interference against their background due to their excellent photoluminescent properties. In recent years, fluorescent nanoelectronic materials have emerged as a novel class of fluorescent materials for fingerprint development research. Here, carbon quantum dots (CQDs) are synthesized using an electrochemical method and utilized as fluorescent nanoelectronic materials in combination with gold nanoparticles (AuNPs) to form a composite (Au/CQDs). The photoelectric properties of Au/CQDs are verified, and a precursor solution for Au/CQDs is prepared using the Wessling method. After the addition of a surfactant and subsequent elimination processes, an Au/CQDs fluorescent nanocolloidal solution is obtained. This solution is applied for the development of visible fingerprints and latent fingerprints on adhesive surfaces. The resulting development images are subjected to enhancement processes such as sharpening, smoothing, and noise reduction using partial differential equations to improve their visual quality. In experiments, under light exposure, Au/CQDs exhibit a higher conversion rate with cyclohexane compared to conditions without light. In the Au/NPs system, the fluorescence of CQDs is effectively quenched due to the rapid electron transfer process within the Au/CQDs system. Moreover, the electrode modified with Au/CQDs shows significantly improved efficiency in decomposing H2O2 compared to conditions without light exposure. After the development with Au/CQDs nanoparticle colloid solution, bright fingerprint patterns are visible under ultraviolet light. As the age of the fingerprint increases, the developed fingerprint has a higher resolution than fresh fingerprints. Image enhancement through partial differential equations results in satisfactory sharp edges and smooth contours in the images.

Development of latent fingerprints by degradable highly-adhering powder——a long-term strategy for the fading of fingerprint residues

The development of highly efficient and harmless reagent for visualization of latent fingerprints (LFPs) on variety substrates is of great importance for criminal investigations. Herein, a kind of “green” and cost-effective fingerprint development powder (polydopamine nanospheres, PDA NSs) is facilely synthesized via self-polymerization of dopamine under mild condition. Due to the abundant functional groups (catechol and amine), PDA-based powder can firmly adhere to the fingerprint residues via supermolecule interactions on various substrates (permeable or not) rapidly. The apparent LFPs from male or female were successfully obtained and analyzed. The fingerprint images exhibited clear first level (fingerprint patterns) and second level (detail features) fingerprint information on the challenging substrates (colored lid, cambered cup, paper, wood, and leather). Even fingerprint aged for more than 90 days on the non-permeable substrate surface can be recognized obviously with extremely lower detection limit. In addition, the gray value analysis further verified the advantage of PDA-based fingerprint development with good contrast, resolution and selectivity. Moreover, the excellent properties of the novel PDA NSs powder endow it highly competitiveness to the commercial low hazard black magnetic powder, which may be expected to make it become an attractive nanomaterial in crime scenes and forensic investigations.

The effect of household corrosive substances on latent fingermark development in the context of deliberate corrosive substance attacks.

Corrosive substance attacks (CSA) are a prevalent issue in the UK with 525 offenses involving a corrosive substance reported to the police in the year ending March 2022. Easy availability, low cost, and concealability in public are common reasons for choosing a corrosive substance as a weapon. The Metropolitan Police revealed that 68% of 1849 CSA cases resulted in no suspect identified or evidential difficulties. There is limited research into the effect of corrosive substances on latent fingermarks. This study aimed to determine the potential for fingermarks to be recovered from surfaces exposed to a household corrosive substance within the context of a deliberate CSA. Natural and sebaceous-loaded fingermarks were exposed to Domestos bleach, Harpic limescale remover (hydrochloric acid-based) and lemon juice. Harpic limescale remover had the most detrimental effect, with only 7.1% of fingermarks (n = 378) exposed being identifiable (defined as sufficient clear ridge detail for identification) after enhancement, followed by bleach with only 10.3% of fingermarks (n = 378) identifiable. Lemon juice had the least detrimental effect on fingermarks, with 40.5% fingermarks (n = 378) identifiable compared to 53.4% for the controls (not exposed to any substance; n = 378). Throughout the study, fewer natural fingermarks were identifiable after exposure to corrosive substances compared to sebaceous fingermarks which was as expected. Overall, this study demonstrated that there is potential to recover latent fingermarks, depending on their composition, following exposure to a household corrosive substance. This area warrants further research to establish best practice to maximize the potential to recover identifiable fingermarks.