Fingerprint Residues Research Articles

Robust synthesis of mono-dispersed spherical silica nanoparticle from rice husk for high definition latent fingermark development

Silica is one of the most functional metalloid oxides with a widespread application as semiconductor, fillers, silicone and ceramic primarily due to its structural versatility. In this work, a robust step-wise thermochemical treatment was successfully formulated for the controlled fabrication of high-purity mono-dispersed spherical silica nanoparticle from rice husk. The silica nanoparticle with the desired morphology was formed in two stages; thermal-assisted seed particle formation followed by particle growth through acidification of the solvent modified sodium silicate solution. The obtained powder was characterised, and the effectiveness of the powder for latent fingermark development across varied donors and surfaces was tested at the introductory level. The formed spherical particles were in the range of 200 to 400 nm, as confirmed by FESEM and HRTEM analysis. Minimising the degree of silica nanoparticle agglomeration notably affected their selectivity to fingermark residue. There was a striking improvement in the selectivity of the silica nanoparticle to fingermark residue. The improvement was attributed to the strong interaction between the silica nanoparticle and the lipid components in the fingermark residue, as compared to the commercial white powder that works solely based on mechanical adherence. Additionally, the size and morphology of the fabricated silica nanoparticle were optimised to enhance the clarity of the developed fingermark. Findings of this study could improve quality of fingermarks obtained in a crime scene due to considerably lower background interference without compromising the effectiveness of fingermark development.

Bright Luminescent Carbon Dots for Multifunctional Selective Sensing and Imaging Applications in Living Cells.

Luminescent carbon dots (CDs) have become attractive materials because of their superior photophysical properties and various potential applications. However, most of the formerly developed CDs only have strong blue emission, which limits their further applications, particularly in bioimaging. Herein luminescent CDs have been successfully synthesized via a one-pot solvothermal process using 4-bromoaniline and ethylenediamine as starting materials. The luminescent CDs emit strong green fluorescence with high quantum yield as well as excellent biocompatibility and biolabeling potentials. At first, the luminescent CDs exhibited high selectivity for phosgene with a turn-off fluorescence detection. The limit of detection was 81 nM, which is sensitive for the determination of phosgene over other competing toxic pollutants. In addition, the luminescent CDs have shown a three-state "on-off-on" emission with the stepwise addition of Ag+ and cysteine (Cys). Luminescent CDs show fluorescence quenching by Ag+ and fluorescence regaining with further addition of Cys, with lower detection limits of 3.9 μM (Ag+) and 3.4 μM (Cys), respectively. The luminescent CDs were utilized to obtain a clear fingerprint. During the drying process, the coffee ring effect and electrostatic interaction between the positive surface charge of amine-functionalized CDs and negatively charged fingerprint residues facilitate the formation of clear fingerprints on different platforms.

Negative Result: Assessing tropolone and its derivatives as chemical fingermark developers on paper surfaces

Tropolone reacts with amino acids to form adducts that generate contrast on highly fluorescent paper surfaces upon UV irradiation. Furthermore, the conjugated seven-membered ring of tropolone enables secondary chemical treatments; demonstrated here using two diazonium salts, 4-methoxybenzenediazonium tetrafluoroborate (4MBD) and 4-nitrobenzenediazonium tetrafluoroborate (4NBD). These produce yellow and red dyed fingermarks, respectively. While tropolone treatment is rapid to effect and compatible with ninhydrin in a detection sequence, the methodology proved less effective than current chemical visualisation treatments. Nevertheless, this work unambiguously demonstrates the reactivity of tropolone towards fingermark residues and may inspire future generations of non-benzenoid chemical visualisation treatments.

Simultaneous imaging of latent fingerprint and quantification of nicotine residue by NaYF4:Yb/Tm upconversion nanoparticles

Numerous investigations have been devoted to visualizing latent fingerprints (LFPs) for personal identification in forensic investigation and age estimation. While simultaneous detection of chemicals in fingerprint residues has yet to be explored. Herein, fluorescent NaYF4:Yb/Tm up-conversion nanoparticles (UCNPs), which can emit blue fluorescence upon 980 nm near-infrared irradiation, have been employed in the imaging of LFPs with high contrast and high sensitivity. The furrows and ridges which provide detailed information of LFP have been displayed clearly by Tm-doped UCNPs. Meanwhile, the quantitation of nicotine residue in LFPs has been achieved based on the blue fluorescence absorbed by I2-nicotine complex, and the data was analyzed by MATLAB with modified OPTA algorithm. It was proved that the established strategy was specific, sensitive, reliable and practical toward nicotine residue in LFPs with a detection limit of 0.05 μg.

Determining Fingerprint Age with Mass Spectrometry Imaging via Ozonolysis of Triacylglycerols.

Despite the common use of fingerprints as a trusted means of identification, no method currently exists to reliably establish the time since deposition of latent fingerprints. A reproducible method of establishing latent fingerprint age would allow forensic personnel to determine if a latent fingerprint was relevant to a crime. This work investigates the ambient aging of triacylglycerols (TGs) and other lipids in latent fingerprint residue utilizing matrix-assisted laser desorption/ionization mass spectrometry imaging. Unsaturated TGs were found to undergo ambient ozonolysis resulting in a decrease over time. At the same time, two series of compounds related to the degradation of unsaturated TGs due to ambient ozonolysis emerged with time and were detectable within a single day of aging. Tracking the degradation of unsaturated TGs over time proved to be relatively reproducible in multiple individuals and is suggested as a means of establishing latent fingerprint age.

Fatty acids as biomimetic replication agents for luminescent metal-organic framework patterns.

Luminescent metal-organic frameworks (MOFs) are known to spontaneously self-assemble on human fingerprints. Here, we investigate the different chemical components of fingerprints and determine that MOF growth is predominantly induced by insoluble fatty acids. This finding shows that these simple biomolecules can be employed for the precise positioning of luminescent MOFs.

The Effect of Temperature and Exposure Time on Stability of Cholesterol and Squalene in Latent Fingermarks Deposited on PVDF Membrane.

Cholesterol and squalene are fatty materials of latent fingermarks that can be utilized for dating methodologies and visualization techniques. Previous studies have suggested these compounds undergo degradation in fingermarks as a function of time (days) and light at ambient temperature. However, studies assessing how their composition changes at low and high temperatures over short periods of time (hours) have not been published previously. Here, we performed quantitative analysis of cholesterol and squalene in natural fingermark residue using PVDF membrane, after exposure to a range of temperatures (-20 to 100°C) for 4 and 8h. We found that levels of both fatty materials remained constant at -20 to 60°C, but both showed significant reduction at 100°C, over short exposure times. These results indicate that cholesterol and squalene are detectable at -20 to 60°C, whereas at 100°C or higher, both are lost due to rapid thermal degradation.

Evaluation of fatty acids in groomed fingerprint by gas chromatographic analysis using various extraction solvents and treatment methods

Extremely small amounts of fatty acids detected in latent fingerprints are important for studying fingerprint visualization and age determination through changes in composition over time. However, methods for efficiently extracting or recovering fatty acids from fingerprints have not been extensively studied. If accurate and stable quantitative estimations are established, age estimates will be possible through a better understanding of the fatty acid composition. The extraction solvent and treatment method are essential factors for achieving a reliable analysis of fatty acids. There have been few previous studies that efficiently compared fatty acids. In this study, fatty acids from sebaceous fingerprint residues were quantified with various extraction solvents and treatment methods and were evaluated with gas chromatography flame ionization detection (GC-FID). All data were analyzed using a statistical method.

Fixing Transient Iodine on Developed Latent Fingermarks.

In the present study, a simple and novel fume-mist technique is described which can be used efficiently to fix the latent fingermarks developed using iodine. It is well known that the residues left over in the fingermarks interact with iodine to give transient brown impressions which disappear in a short time. Also, iodine forms colored complexes with various organic solvents. Based on iodine-fingermark interaction and iodine-solvent complex formation, latent fingermarks were developed on paper surface using iodine fumes which were subsequently fixed by spraying polar and nonpolar solvents. The fingermarks developed with this technique were not only clear but also permanent in nature. The interaction of fingermark residue, iodine, and solvent forming a ternary structure is believed to be a possible reason for the stability of iodine-developed fingermarks. Ease of method, availability of chemicals, and minimum training make the method adaptable in routine development of forensic fingermarks present on paper surface.

Revealing the Elemental Distribution within Latent Fingermarks Using Synchrotron Sourced X-ray Fluorescence Microscopy.

Fingermarks are an important form of crime-scene trace evidence; however, their usefulness may be hampered by a variation in response or a lack of robustness in detection methods. Understanding the chemical composition and distribution within fingermarks may help explain variation in latent fingermark detection with existing methods and identify new strategies to increase detection capabilities. The majority of research in the literature describes investigation of organic components of fingermark residue, leaving the elemental distribution less well understood. The relative scarcity of information regarding the elemental distribution within fingermarks is in part due to previous unavailability of direct, micron resolution elemental mapping techniques. This capability is now provided at third generation synchrotron light sources, where X-ray fluorescence microscopy (XFM) provides micron or submicron spatial resolution and direct detection with sub-μM detection limits. XFM has been applied in this study to reveal the distribution of inorganic components within fingermark residue, including endogenous trace metals (Fe, Cu, Zn), diffusible ions (Cl-, K+, Ca2+), and exogeneous metals (Ni, Ti, Bi). This study incorporated a multimodal approach using XFM and infrared microspectroscopy analyses to demonstrate colocalization of endogenous metals within the hydrophilic organic components of fingermark residue. Additional experiments were then undertaken to investigate how sources of exogenous metals (e.g., coins and cosmetics) may be transferred to, and distributed within, latent fingermarks. Lastly, this study reports a preliminary assessment of how environmental factors such as exposure to aqueous environments may affect elemental distribution within fingermarks. Taken together, the results of this study advance our current understanding of fingermark composition and its spatial distribution of chemical components and may help explain detection variation observed during detection of fingermarks using standard forensic protocols.

Controlling fingermark variability for research purposes: A review

AbstractFingermark detection is a very active field of research in forensic science, with many different strategies currently investigated to always improve detection rate. However, each new technique has first to be optimized, assessed and validated with many fingermarks from multiple donors across a wide variety of substrates before being included into laboratories operating procedures. This process often requires the collaboration of research groups and operational laboratories from different countries, and it takes several years for a new method to be applied routinely in casework. One particular challenge that makes the process from R&D to operations complicated is the significant intrinsic within‐ and between‐source variability of fingermarks. Many studies partially addressing fingermark variability have been reported but a comprehensive approach to the problem is yet to be found. This review describes the factors of fingermark variability and provides an extensive overview of various strategies implemented to control it. The use of artificial fingermarks or simulants, containing some of the most abundant compounds found in fingermark residue has been investigated by some research teams. However, most of these formulations are too simplistic and can only be used to assess a restrictive number of detection techniques, such as amino acid reagents. Practical applications of artificial fingermarks such as test strips and proficiency testing are reviewed. The advantage and challenges of using artificial fingermarks in the first stages of fingermark detection research are presented.This article is categorized under: Forensic Chemistry and Trace Evidence > Fingermarks and Other Marks

Investigations into sampling approaches for chemical analysis of latent fingermark residue

The quantitative variation in latent fingermark deposits sampled from the same donor (intra-donor) poses considerable challenges to studies into the chemical composition of latent fingermarks. The work presented here investigates approaches to the sampling of latent fingermark residues within this context. The amount of squalene in fingermarks deposited on non-porous surfaces, determined by GC–MS, was used as an indicator of the amount of non-polar material present. It was found that the percentage difference of squalene between deposits from two hands at a given time, without controlling the deposition force, was in the range of 4–100%. This was reduced to 0–44% in alternative sampling approaches where deposition force was controlled. These results demonstrate the significant influence of sampling on subsequent chemical analysis of fingermark residues, and offer possible sampling strategies to overcome issues associated with intra-donor variation.

Сurrent Issues in Sebaceous Sweat Fingerprint Residue Visualization on Fired Cartridge Cases

This article focuses on issues concerning discovery of hands deposits on cases fred with certain models of fre weapons – 5.45 mm assault rifle АК-74М, 9 mm Makarov gun, 7,62 mm TT gun. Five persons left in turn on each of the above ammunition rounds intentionally qualitative hand traces, following which a shot was fred. After the shot the fre shot cases were collected and packed, avoiding contact between side surfaces and package material. The possibilities of discovery hand deposits on fred cases were determined by using reductive-oxidative and physical-chemical methods. The mechanism of “latent degradation” of hand deposits on cases formed before fring caused by the influence of the shot fact (high temperature, static and dynamic power contact of fred case with gun chamber walls) has been reviewed.

Latent Fingerprint Visualization and Subsequent DNA Extraction Using Electron Beam Evaporation of Metallic Ultra-Thin Films

Background: Proper detection and subsequent extraction of biological evidence are crucial for crime scene reconstruction. Vacuum metal deposition is currently an effective technique used in latent fingerprint development. However, the established procedures commonly undergo a direct plasma bombardment, a high ablation fluence and/or a high temperature process in vacuum metal deposition system. Method: In this work, electron beam evaporation (EBE) was used to investigate the development of latent fingerprints and subsequent DNA extraction of biological evidence. Gold or copper is preferentially nucleated on the background surfaces rather than the fingerprint residues due to the difference of the nature of the surface, which indicates that the gold / copper and copper agglomerates are binding to the fingerprint valleys not the ridges of the fingerprint, revealing bright patterns with excellent ridge detail clarity on black surfaces. Result: It is demonstrated that the co-extraction of the latent fingerprints and DNA is attributed to electron beam evaporated one-step process with relatively low energy bombarding energetic species and neutral particles, less possibility of contamination and without toxic and fluorine-based gases. Conclusion: Our results demonstrate that EBE is a promising technique for the latent fingerprints and DNA co-extraction.

Fluorescence of 1,2-Indanedione with Amino Acids Present in the Fingerprint Residue: Application in Gender Determination.

1,2-indanedione is used for latent fingerprint visualization on porous surfaces. In this paper, fluorescence spectra of 1,2-indanedione after reacting with 21 individual amino acids present in latent fingerprints residue were measured in water-methanol solutions. The fluorescence intensity depends on the amino acid used, while the fluorescence peak does not change much. The concentration of amino acids in fingerprint residue in females is almost the double of their concentration in males. This property combined with fluorescence of 1,2-indanedione-amino acids compounds is used for gender determination, by comparing the fluorescence intensity peaks in the same experimental conditions. In this preliminary study, the fluorescence signal from the samples representing females was almost two times the signal for samples representing males. In addition to the reduction by almost 50% of the number of suspects in a criminal research case, these results could be helpful in gaining some knowledge about the papillary residue composition.

Combination of electrospray deposition technology of TiO2 nanoparticles and MALDI FTICR MSI for identification of fingerprint morphology and latent components

In fingerprint recognition, besides the physical shape information afforded by fingerprint enhancement techniques (FET), in recent years, more and more efforts are focused on researching the chemical composition of a fingerprint residue. In this work, electrospray deposition method was elaborately used to softly and homogenously deposit the physical enhancers of FET, TiO2 nanoparticles (TiO2 NPs), onto fingerprints. The results showed that this type of deposition was nondestructive to the fingerprint morphology and provided the physical shape information containing all level features. Concurrently, the TiO2 NPs demonstrated as a better matrix of matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) for analysis and imaging of latent components in fingerprint, including endogenous substances like triacylglycerols (TAGs), diacylglycerols (DAGs) and cholesterol esters (CEs), and exogenous substances such as certain ingredients in hand lotion. The chemical compositions in fingerprint are closely related to individual metabolites and individual lifestyles, and identification of these compositions by Fourier transform ion cyclotron resonance (FTICR) MS is extremely beneficial for forensic analysis. The combinations of electrospray deposition technology of TiO2 NPs and MALDI FTICR MSI for identification of fingerprint morphology and latent components provide dual-modes fingerprint recognition for forensic science.

Highly-selective recognition of latent fingermarks by La-sensitized Ce nanocomposites via electrostatic binding.

Herein, a series of binuclear (Ce,La) nanocomposite fluorescent powders was elaborately designed for highly-selective recognition of latent fingermarks by the powder dusting method, which were proved to interact with fingermark residues via electrostatic binding without any damage to touch-DNA.

Application of hyperspectral imaging and mass spectrometry imaging technique to fingerprint visualization and trace analysis

Developing on advanced light sources, especially those applied in the areas of spectral imaging and mass spectrometry imaging, has made the trace analysis feasible and more reliable. These techniques show great potentials in various fields including forensic science, environment, food, pharmaceuticals, archaeology, etc. In many cases of trace analysis, it is expected to obtain both the spatial distributions and chemical compositions of the target objects. Through the combination of imaging technology with optical spectroscopy and mass spectrometry, it is possible to detect the trace chemicals on the surface of various materials as well as their spatial distributions, thus improving the accuracy of detection and the range of application. Moreover, trace analysis based on such methods can reduce or even avoid the use of special chemical reagents, and is compatible with the traditional chemical detection methods. In the paper, we focus on fingerprint visualization and analysis, as a typical trace analysis issue, to discuss the recent progress of the applicable chemical imaging technologies based on the advanced light sources. The effect of latent fingerprint development depends on not only features of fingerprint carrying object, but also the characteristics of fingerprint residues. In this paper, we provide an overview of two technical approaches: specific component targeted chemical imaging and nondirective chemical imaging. We describe the major technologies involved in this field, including visible-near infrared chemical imaging, mid-infrared chemical imaging, Raman imaging, and mass spectrometry imaging.

Surface coatings including fingerprint residues can significantly alter the size and shape of bloodstains

When conducting a blood pattern analysis (BPA) the size, shape, distribution, and location of bloodstains found at a crime scene may be critical in forming a hypothesis as to what transpired during a bloody event. Prior studies have demonstrated that the size and shape of a bloodstain on a smooth surface are determined from impact dynamics and to a lesser degree by the target material itself. Yet, these studies have relied on clean surfaces, and it is unclear whether the presence of microscopic coatings and residues could significantly alter the size or shape of the dried stain. Here, in the present work, experiments are conducted to demonstrate that various coatings, such as the sebaceous residue from a latent fingerprint, can dramatically alter the size and shape of the stain from the moment of impact through the drying process. These experiments also highlight that a drop impacting a tilted superhydrophobic-coating glass substrate can cause the blood drop to completely recoil without leaving a stain. Relying on a combination of high-speed and time-lapse photography, the specific stages in the stain evolution responsible for the deviations from the current models are identified. At a relatively low impact velocity, the stain sizes on the coated glass surfaces were 35–72% smaller than on the clean glass surface. At a higher impact velocity, the stains on the coated surfaces were not only smaller, but also contained drop spatter around the primary stain that was not observable in the absence of the microscopic coatings. The reduction in bloodstain size did not appreciably change when a chemical was added to deactivate the anticoagulant and allow the blood to clot.

Prediction of DNA concentration in fingermarks using autofluorescence properties

During criminal investigations trace DNA samples, including fingermarks, are submitted to laboratories for short tandem repeat (STR) analysis. For most common STR analysis systems a minimum amount of input DNA is required. Upon intake by the forensic laboratory the DNA concentration is estimated using quantitative polymerase chain reaction (qPCR) analysis after which most fingermarks are excluded. To tackle the problem of unnecessary processing in the lab, our study aimed to develop a method, which is able to predict the DNA content in fingermarks directly at the crime scene. Upon excitation with a UV Crime-lite, fingermark residues have autofluorescent properties. We hypothesize that the intensity of the autofluorescence signal of the fingermark content correlates to the DNA concentration in fingermarks. In this study, 164 fingermarks were examined on their autofluorescence intensity when excited at 365nm, the number of nucleated cells, their DNA concentration and the completeness of the STR profiles. No significant correlation was observed between the DNA concentration in fingermarks and the autofluorescence signal, indicating that a high amount of autofluorescence, thus a high amount of biomaterial, does not necessarily guarantee a higher amount of DNA. In addition, the completeness of the STR profiles did not correlate to the autofluorescence signal of fingermarks. A moderate correlation was found between the predicted DNA quantity, based on the number of nucleated cells and the DNA quantity. In summary, the autofluorescence signal of fingermarks cannot directly be used as a guide to select fingermarks for DNA analysis directly at the crime scene. However, predicting the amount of DNA using a sensitive and specific DNA staining method can probably be used to estimate the DNA concentration in touch samples.