The Compatibility of Fingerprint Visualization Techniques with Immunolabeling

The chemical composition of a fingermark potentially holds a wealth of information about the fingermark donor, which can be extracted by immunolabeling. Immunolabeling can be used to detect specific components in fingermarks; however, to be applicable in the forensic field, it should be compatible with commonly used fingerprint visualization techniques. In this study, the compatibility of immunolabeling with two different fingerprint visualization techniques, magnetic powdering and ninhydrin staining, was investigated on fingermarks deposited on glass and on nitrocellulose membranes. With dermcidin as antigen of interest, immunolabeling was performed successfully on all developed fingermarks. We can conclude that immunolabeling is compatible with magnetic powdering and ninhydrin staining, which can be of great forensic value.     

Development of Latent Fingermarks on Surfaces of Food‐A More Realistic Approach

Latent fingermark developing methods from food (mandarin, egg, banana, apple, potato, carrot, eggplant, onion, bell pepper, and tomato) surface has been studied by 10 methods, including powdering method, small particle reagent method, and cyanoacrylate fuming method. The foods were stored under two conditions (room temperature and refrigerator) before fingermark deposition and aged for 2, 24, 48, and 72 h before fingermark development. In most of the food surfaces used in this study, cyanoacrylate fuming with 80% relative humidity was superior to the powder or small particle reagent methods. The quality of the fingermarks varied depending on the storage conditions before the fingermark deposition (in the refrigerator or at ambient temperature) and the time elapsed since the fingermark deposition. However, the storage conditions before the fingermark deposition and the time elapsed since the fingermark deposition did not show any correlation with the quality of the fingermark.     

Evaluation of Lumicyano™ cyanoacrylate fuming process for the development of latent fingermarks on plastic carrier bags by means of a pseudo operational comparative trial

There are a number of studies discussing recent developments of a one-step fluorescent cyanoacrylate process. This study is a pseudo operational trial to compare an example of a one-step fluorescent cyanoacrylate product, Lumicyano™, with the two recommended techniques for plastic carrier bags; cyanoacrylate fuming followed by basic yellow 40 (BY40) dyeing and powder suspensions. 100 plastic carrier bags were collected from the place of work and the items were treated as found without any additional fingermark deposition. The bags were split into three and after treatment with the three techniques a comparable number of fingermarks were detected by each technique (average of 300 fingermarks). The items treated with Lumicyano™ were sequentially processed with BY40 and an additional 43 new fingermarks were detected. Lumicyano™ appears to be a suitable technique for the development of fingermarks on plastic carrier bags and it can help save lab space and time as it does not require dyeing or drying procedures. Furthermore, contrary to other one-step cyanoacrylate products, existing cyanoacrylate cabinets do not require any modification for the treatment of articles with Lumicyano™. To date, there is little peer reviewed articles in the literature on trials related to Lumicyano™ and this study aims to contribute to fill this gap.     

The detection and enhancement of latent fingermarks using infrared chemical imaging

The use of a new technique, Fourier transform infrared (FTIR) chemical imaging, has been demonstrated for the enhancement of latent fingermarks on a number of surfaces. Images of untreated fingermarks on glass backgrounds with excellent ridge detail were acquired using infrared chemical imaging. High quality fingermarks on glass backgrounds were also developed using ethyl cyanoacrylate (super glue) fuming and subsequent infrared chemical imaging. This new method allows the collection of images from backgrounds that traditionally pose problems for current fingermark detection methods. The background may, for example, be highly colored, have a complex pattern, or possess other pattern or image characteristics that make it difficult to separate fingermark ridges using traditional optical or luminescent visualization. One background that has proven to be a challenging surface for the development of latent fingermarks is the Australian polymer banknote. To demonstrate the power and applicability of infrared chemical imaging, fingermarks fumed with ethyl cyanoacrylate were successfully imaged from Australian polymer banknotes.     

Fingermark visualisation on metal surfaces: An initial investigation of the influence of surface condition on process effectiveness

Fingermark recovery from metal surfaces is an area of operational interest, both from the association of metals with weapons used in violent crime and from the increasing incidence in metal theft. This paper reports a feasibility study into the effectiveness of a range of fingermark visualisation processes in developing fingermarks on clean metals (brass, bronze and stainless steel), and on the same metals after prolonged exposure to an outdoor environment. Scanning electron microscopy (SEM) was used to investigate how the surface type and condition could influence the development of fingermarks for each of the processes used. It was found that the behaviour observed varied between each of the processes (cyanoacrylate fuming, Lumicyano?, gun blueing and carbon-based powder suspension). In some cases the chemical composition of the surface affected the development of the mark more than the surface condition, and in other cases the reverse was true. The best performing processes differed according to the surface type and condition, with cyanoacrylate fuming processes working best on brass and bronze, and powder suspensions being better on stainless steel. These preliminary results reinforce the need to take into account both surface type and condition before selection of the most effective fingermark visualisation process and demonstrate the value of techniques such as SEM in developing a fundamental understanding of the interactions between fingermarks and surfaces.     

Development of Latent Fingermarks from Rocks and Stones

Since the beginning of recorded history, stones have been used in the commission of crimes due to their widespread availability. Stones can be used as a lethal weapon that sometimes might be the only evidence in a serious case. The common perception, even in professional fingermark circles, is that stones do not yield identifiable latent fingermarks. The authors of this research paper examined the feasibility of developing fingermarks from seven types of stones using three latent fingermark techniques: magnetic powder, cyanoacrylate fuming, and ninhydrin. The paper will demonstrate that by classifying stones and rocks according to their natural properties (porosity, permeability, and the nature of surface area), even application of the simplest development techniques can produce good results. In conclusion, chert and limestone yielded the most qualitative and quantitative results using magnetic powder. The time factor is also important in recovering latent fingermarks on stones and rocks.     

Fingermark detection on non-porous and semi-porous surfaces using YVO4:Er,Yb luminescent upconverting particles

This article describes the use of an anti-Stokes luminescent material (upconverter), yttrium vanadate doped with ytterbium and erbium (YVO(4):Er,Yb), for the development of latent fingermarks on a range of non-porous surfaces. Anti-Stokes luminescent materials emit light at shorter wavelengths than the excitation wavelength. This property is unusual in both natural and artificial materials commonly found as exhibits in forensic science casework. As a result, fingermark detection techniques based on anti-Stokes luminescence are potentially extremely sensitive and selective. Latent fingermarks on non-luminescent and inherently luminescent substrates, including Australian polymer banknotes (a well-known 'difficult' surface), were developed with YVO(4):Er,Yb by dry powder and wet powder techniques. The effectiveness of YVO(4):Er,Yb for fingermark detection was compared with that of cyanoacrylate fuming and of sodium yttrium tetrafluoride doped with ytterbium and erbium (NaYF(4):Er,Yb). The results illustrate some benefit of luminescent up-converting phosphors over traditional luminescence techniques for the detection of latent fingermarks.     

Understanding the chemistry of the development of latent fingerprints by superglue fuming

Cyanoacrylate fuming is a widely used forensic tool for the development of latent fingerprints, however the mechanistic details of the reaction between the fingerprint residue and the cyanoacrylate vapor are not well understood. Here the polymerization of ethyl-cyanoacrylate vapor by sodium lactate or alanine solutions, two of the major components in fingerprint residue, has been examined by monitoring the time dependence of the mass uptake and resultant polymer molecular weight characteristics. This data provides insight into the molecular level actions in the efficient development of latent fingerprints by superglue fuming. The results show that the carboxylate moiety is the primary initiator of the polymerization process and that a basic environment inhibits chain termination while an acidic environment promotes it. The results also indicate that water cannot be the primary initiator in this forensic technique.     

An investigation into the use of a portable cyanoacrylate fuming system (SUPERfume®) and aluminum powder for the development of latent fingermarks

Abstract: Few techniques offer “in situ” methods of friction ridge skin mark development. “In situ” development reduces mark transportation, degradation, and often cost. The effectiveness of cyanoacrylate fuming using the SUPERfume^® and dusting with aluminum powder for latent fingermark development on several nonporous surfaces, stored in various temperature environments for time periods up to 52 weeks, was investigated. Five thousand and four hundred latent fingermarks were deposited under controlled conditions and graded. The results suggested that cyanoacrylate fuming (SUPERfume^®, Foster and Freeman, U.K.) was more effective at developing latent fingermarks on textured and smooth plastic surfaces and for marks stored in temperatures of 37°C, whereas aluminum powder was more effective on glass, enameled metal paint, and varnished wood, and for storage temperatures below 20°C. There were no significant benefits to using either technique for marks older than 24 h, but it was possible to develop fingermarks following 52 weeks of storage using both techniques.     

Preparation of cyanoacrylate derivatives and comparison of dual action cyanoacrylate formulations

The use of cyanoacrylate followed by fluorescent reagents is well known in the field of fingermark visualisation. Treatment with fluorescent reagents that stain the cyanoacrylate deposits will not only enhance the visibility of fingermarks previously thought unusable, but also reveal previously unseen marks. Downside of this approach is the exposure of the evidential material to large amounts of solvent, such as water, methanol and ethanol, thereby potentially destroying other forensic traces.New cyanoacrylate derivates with fluorescent and UV-active properties can be used for one step dual action visualisation of latent fingermarks. Increased optical properties can be achieved by addition of functional groups via the Steglich esterification of cyanoacetic acid with N-(3-dimetylaminopropyl)-N′-ethylcarbodiimide (EDC). The UV-active ester can be created via the Knoevenagel condensation with formaldehyde to form poly-cyanoacrylate. These poly-cyanoacrylates can be depolymerised to form monomer cyanoacrylates.In this paper we compare these ethylcyanoacrylate derivatives with commercially available cyanoacrylate formulations.We have shown that the use of poly-cyanoacrylate derivatives can yield fully developed fingerprints. The initiator of the polymerisation reaction towards novel reagents can be altered according to the need for particular optical properties.     

Evaluation of the one-step Lumicyano™ used in the visualisation of fingermarks on fabrics

This study consisted of three parts to evaluate the performance of Lumicyano? on a variety of fabrics. One part assessed the impact of dye percentage (8%, 9% and 10%) on visualisation of fingermark detail and luminescent brightness in split grab marks. A 9% dye produced the highest quality detail of grab impressions with least interference from background fluorescence. The second part investigated the optimal relative humidity (RH, 75–84%) for certain fabric types using Lumicyano on split, six-series depletion fingermarks. It was concluded that the recommended RH of 80% remained the ideal cyanoacrylate fuming environment. The final and third part of this study determined the impact of sequential addition of Basic Yellow 40 (BY40) on Lumicyano compared to traditional cyanoacrylate (CA) followed with BY40 application. Results from this study demonstrated that Lumicyano on its own developed fingermarks with superior quality to Lumicyano with sequential addition of BY40 or traditional cyanoacrylate followed by BY40. Inclusion of more fabrics, donors and longer ageing periods should be explored in future studies to determine what frameworks are best for certain types of fabrics.     

Investigation of hydrogen cyanide generation from the cyanoacrylate fuming process used for latent fingermark detection

Cyanoacrylate fuming is one of the most common techniques employed for the detection of latent fingermarks on non-porous surfaces such as plastic and glass. The technique is generally applied by exposing items of interest to the vapours generated by heating a suitable quantity of commercial cyanoacrylate adhesive. In this study, the potential for highly toxic hydrogen cyanide (HCN) to be generated from the overheating of cyanoacrylate was investigated. Two commercial cyanoacrylate adhesives and two quantitative methods for the determination of HCN were employed: (i) the sodium picrate method; and (ii) the picrate-resorcinol method. (13)C nuclear magnetic resonance (NMR) analysis was used to confirm the presence of cyanide. In addition, the thermal decomposition of cyanoacrylate was studied using simultaneous thermogravimetric and differential thermal analysis (TGA-DTA). It was determined that detectable and quantifiable amounts of HCN were generated from the thermal decomposition of cyanoacrylate monomer and polymer at temperatures as low as 200 °C. Using an optimised picrate-resorcinol method, it was shown that around 10 μg of HCN could be generated from the heating of 1g of cyanoacrylate monomer at 200 °C. For one of the adhesives tested, this increased to above 100 μg of HCN when 1g of cyanoacrylate monomer was heated at 280 °C. Recommendations are provided that, if followed, should ensure that the cyanoacrylate fuming process can be safely applied with minimal risk to the operator.     

A comparative evaluation of the disulfur dinitride process for the visualisation of fingermarks on metal surfaces

The disulfur dinitride process for fingermark visualisation was first reported a decade ago, with promising results obtained for a range of materials including metals. However, the friction sensitive nature of the material and difficulty of synthesis made routine use difficult. Many of these issues have since been addressed, making equipment and chemicals available to build an understanding of how the effectiveness of disulfur dinitride compares to other fingermark visualisation processes currently used on metal surfaces. This enables more informed advice to be given on selection of processes for treatment of metal items, an area of operational interest that encompasses weapons used in violent crime and the increasing incidence in metal theft. This paper reports a comparative study into the effectiveness of disulfur dinitride, cyanoacrylate fuming, vacuum metal deposition, gun blueing and wet powder suspensions on brass, bronze, copper and stainless steel. Experiments were conducted with the surfaces exposed to a range of environments including long term ageing, water/detergent washing, acetone washing and high temperature exposure. The results indicate that disulfur dinitride is an effective process for fingermark visualisation on metal surfaces, including those exposed to adverse environments, and may offer potential improvements over existing processes for those surfaces. Further work, including pseudo-operational trials, is recommended.     

Processes involved in the development of latent fingerprints using the cyanoacrylate fuming method

Chemical processes involved in the development of latent fingerprints using the cyanoacrylate fuming method have been studied. Two major types of latent prints have been investigated-clean and oily prints. Scanning electron microscopy (SEM) has been used as a tool for determining the morphology of the polymer developed separately on clean and oily prints after cyanoacrylate fuming. A correlation between the chemical composition of an aged latent fingerprint, prior to development, and the quality of a developed fingerprint has been observed in the morphology. The moisture in the print prior to fuming has been found to be more important than the moisture in the air during fuming for the development of a useful latent print. In addition, the amount of time required to develop a high quality latent print has been found to be within 2 min. The cyanoacrylate polymerization process is extremely rapid. When heat is used to accelerate the fuming process, typically a period of 2 min is required to develop the print. The optimum development time depends upon the concentration of cyanoacrylate vapors within the enclosure.     

Chemical Imaging of Human Fingermark by X-ray Photoelectron Spectroscopy (XPS)

X-ray photoelectron spectroscopy (XPS) is a widely used technique to characterize the surface chemistry of materials. It plays a crucial role in accessing qualitative and quantitative information and in detecting the presence of chemical functional groups on the surface of any material. The forensic methods available to detect and identify elements and organic/inorganic compounds are often destructive, so evidence cannot be re-analyzed. However, XPS allows rapid analysis of samples without damaging them. Recently, an increasing number of forensic researchers have begun to study certain chemical information on fingermarks. In this study, the authors aimed to present the applicability and power of XPS imaging in fingermark analysis which can also provide specific information about the fingermark chemical composition. Herein, monochromated X-ray (Al Kα) spot size was fixed at 50 μm. XPS mapping resulted in the acquisition of spectra at each pixel, in an array of 41 × 30 pixels with a step size of 50 μm. Then, a simple discussion has been made about how the scanned surface spectrum and basic snapshot spectra are used to identify different components at a fingertip of a scanned surface area (~3 mm²). Hence, a fingermark pattern contaminated with caffeine, TiO₂, and Pb/PbO deposited on the silicon wafer can be chemically mapped and visualized by XPS using principal component analysis (PCA). Thus, the present study showed the possible applicability of XPS for the identification of illicit drugs of abuse, gunshot residue, and skin care products on latent fingermark by mimicking a crime scene evidence.     

The Effects of Polymer Pigmentation on Fingermark Development Techniques

The effectiveness of latent fingerprint development techniques is heavily influenced by the physical and chemical properties of the deposition surface. The use of powder suspensions is increasing for development of prints on a range of surfaces. We demonstrate that carbon powder suspension development on polymers is detrimentally affected by the presence of common white pigment, titanium dioxide. Scanning electron microscopy demonstrates that patches of the compound are clearly associated with increased levels of powder adhesion. Substrates with nonlocalized titanium dioxide content also exhibit increased levels of carbon powder staining on a surface‐wide basis. Secondary ion mass spectrometry and complementary techniques demonstrate the importance of levels of the pigment within the top 30 nm. The association is independent of fingermark deposition and may be related to surface energy variation. The detrimental effect of the pigment is not observed with small‐particle reagent (MoS₂ SPR) or cyanoacrylate (superglue) fuming techniques that exploit different development mechanisms.     

Identification of a Suspect in a Murder Case through Recovery of Fingermarks from a Fired Cartridge Case

During the period of one year, the Police of the State of Espírito Santo in Brazil analyzed 1,431 cartridge cases obtained from crime scenes and seizures. The cartridges were subjected to a development sequence (cyanoacrylate fuming + gun bluing + fluorescent dying), and panoramic images of the developed fingermarks were generated based on the photographs taken during the rotation of the cartridges. Ridge details were observed in 50 cartridges, but only in 5 cartridges, the marks were considered with value for identification. The fingermarks were searched in the Automated Fingerprint Identification System (AFIS) of the Brazilian Federal Police and, in one case, it was possible to obtain the suspect's identification. In our knowledge, this is the first case in Brazil of identification of a suspect based on a fingermark recovered from a fired cartridge case.     

A comparison of the use of vacuum metal deposition versus cyanoacrylate fuming for visualisation of fingermarks and grab impressions on fabrics

Both vacuum metal deposition (VMD) and cyanoacrylate fuming (CAF) are techniques used to visualise latent fingermarks on smooth non-porous surfaces such as plastic and glass. VMD was initially investigated in the 1970s as to its effectiveness for visualising prints on fabrics, but was abandoned when radioactive sulphur dioxide was found to be more effective. However, interest in VMD was resurrected in the 1990s when CAF was also used routinely. We now report on studies to determine whether VMD or CAF is the more effective technique for the detection of marks on fabrics. Four different fabrics, nylon, polyester, polycotton and cotton, were utilised during this study, along with 15 donors who ranged in their age and ability to leave fingermarks, from good to medium to poor, thus reflecting the general population. Once samples were collected they were kept for a determined time (1, 2, 3, 4, 5, 6, 7, 14, 21 or 28 days) and then treated using either the gold and zinc metal VMD process or standard cyanoacrylate fuming.The smoother fabrics, such as nylon, consistently produced greater ridge detail whereas duller fabrics, like cotton tended only to show empty prints and impressions of where the fabric had been touched, rather than any ridge details. The majority of fabrics did however allow the development of touch marks that could be targeted for DNA taping which potentially could lead to a DNA profile. Of the two techniques VMD was around 5 times more effective than CAF, producing a greater amount of ridge detail, palmar flexion creases and target areas on more samples and fabrics.     

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.     

“502”真空熏显手印技术的应用现状

在我国,“502”加温加湿熏显手印技术已广为普及,但“502”真空熏显手印技术人们了解很少。本文通过介绍“502”熏显手印技术的发展,着重介绍真空熏显方法的特点。