Reactions of latent prints exposed to blood

We explored whether an undeveloped latent print (fingermark) exposed to blood and later developed by enhancement with blood reagents such as amido black (AB) or leucocrystal violet (LCV) could appear as a genuine blood mark. We examined three different experimental conditions. In Experiment I, fingermark residue only was tested, as a control to confirm that fingermark residue alone does not react with the blood reagents AB and LCV. Experiment II investigated whether latent fingermarks exposed to blood dilutions could be treated with AB or LCV and subsequently appear as a genuine blood mark enhanced with AB or LCV. Experiment III tested whether latent fingermarks exposed to whole blood could be processed with AB or LCV and subsequently appear as a genuine blood mark enhanced with AB or LCV.The present study found that indeed, fingermark residue alone does not react with the blood reagents AB and LCV. In Experiment II, an interaction occurred between the fingermark residue and the diluted blood that caused the ridges to appear a red color. In the present study, this interaction is called a faux blood mark. While the faux blood mark phenomenon occurred most often following exposure to diluted blood, it did not occur consistently, and a predictable pattern could not be established. However, the reaction occurred more frequently following extended fingermark residue drying times. Faux blood marks are distinguishable from genuine blood marks prior to enhancement with blood reagents. Following treatment with blood reagents, it became increasingly difficult to determine whether the enhanced mark was a genuine blood print or a latent fingermark exposed to diluted blood. Latent fingermarks exposed to whole blood often resulted in a void prior to enhancement, but following treatment with blood reagents, were difficult to distinguish from a genuine blood mark enhanced with blood reagents.     

Application of mist to fingermark detection: Misting with high-boiling-point liquid containing p-dimethylaminocinnamaldehyde and cyanoacrylate

In order to detect latent fingerprints that could be damaged by liquid or powder reagents, non-destructive processes such as gaseous reagents have been developed. In this report, we propose the use of fine mist generated when hot vapor of high-boiling-point liquids is rapidly cooled by surrounding air for fingermark detection. Octyl acetate (OA), 2-phenoxyethanol (2PE), and methyl decanoate (MD) were found to efficiently produce mist when heated to 230°C. By combining these liquids with p-dimethylaminocinnamaldehyde (DMAC) and cyanoacrylate (CN), our team demonstrated effective fluorescence staining of cyano-treated fingermarks using DMAC/OA misting or DMAC/2PE misting, and one-step fluorescence detection of latent fingermarks without cyanoacrylate treatment using DMAC/OA/CN misting or DMAC/MD/CN misting. Fingermark fluorescence was efficiently observed by excitation with a blue LED light (max. wavelength 470 nm) equipped with an interference filter and passing through a 520 nm long-pass filter. We successfully obtained fluorescent images from fingermarks on several substrate materials using the developed misting method.     

Novel O‐propyl,S‐propyl,and N‐propyl substituted 1,4‐naphthoquinones and 1,4‐anthraquinones as potential fingermark development reagents for porous surfaces

Lawsone is a 2‐substituted‐1,4‐naphthoquinone derivative, which has been proposed as an alternative to the reagents currently used for fingermark detection on porous surfaces. 2‐substituted‐anthraquinones, which contain an additional conjugated benzene ring, have a similar chemical structure to that of lawsone. In this study, a new series of 2‐substituted‐1,4‐naphthoquinones and 2‐substituted‐1,4‐anthraquinones were synthesized and completely characterized by¹H NMR,¹³C NMR, IR, and HPLC‐TOF/MS analyses. All newly synthesized 2‐substituted‐1,4‐quinones were investigated for their ability to develop latent fingermarks on porous surfaces, and this ability was compared with that of lawsone. Each fingermark developed was graded using an established method; thus, quantitative data were attributed to each fingermark. It has been demonstrated that the 1,4 ‐ quinones react with amino acids present in latent fingermarks on selected paper surfaces to produce faint yellow‐orange impressions, which exhibit strong photoluminescence when illuminated with a forensic light source at 440 nm and observed through a red filter. None of the compounds caused background darkening. The results obtained were generally similar to those of lawsone, however, 8‐dibromo‐2‐(propylamino)naphthalene‐1,4‐dione and 5,8‐dibromo‐2‐(propylthio)naphthalene‐1,4‐dione yielded better results for copier paper and colored (blue) copier paper used in this analysis. To the best of our knowledge, this is the first study to examine the role of 1,4‐anthraquinone derivatives as potential fingermark development reagents. The results indicate that 1,4‐quinones have a potential to be used as reagents for enhancement of latent fingermarks.     

An investigation into the enhancement of fingermarks in blood on fruit and vegetables

A number of studies have reported the successful enhancement of latent fingermarks on fruit and vegetables. A study was set up to identify the most effective technique for the enhancement of fingermarks in blood on various fruit and vegetables. The enhancement techniques targeted different components in blood and consisted of protein stains (e.g. acid black 1), peroxidase reagents (e.g. leuco crystal violet) and amino acid stains (e.g. ninhydrin). Different variables such as the ageing periods of the marks and a diminishing series were employed to assess the suitability and sensitivity of the enhancement techniques.Overall, the use of different protein stains appeared to be the most effective techniques for the enhancement of fingermarks in blood on fruit and vegetables. In addition, the aubergine and cucumber skins appeared to be the most responsive surface to the different chemical techniques during enhancement. On the contrary, little or no enhancement was achieved for fingermarks in blood on the nectarine fruit.     

An investigation into the enhancement of fingermarks in blood on paper with genipin and lawsone

The abilities of two natural products, genipin and lawsone, to enhance blood contaminated fingermarks on papers of various porosities and colour were investigated and compared to the routinely used amino acid reagents, ninhydrin and 1,8-diazafluoren-9-one (DFO).Fingermarks in blood were deposited as a split depletion series on various paper types and colours for ageing periods of 6 weeks, 4 weeks, 2 weeks and 1 week before enhancement. The developed marks were observed under different lighting conditions, recorded and graded by way of attributing quantitative data to each series.Results indicated that while genipin showed some potential as a reagent for the enhancement of latent fingermarks, it displayed no suitability for the enhancement of fingermarks in blood on paper. Lawsone also failed to successfully enhance either type of fingermark. Upon comparison of the results with those of ninhydrin and DFO it was found that ninhydrin displayed the highest success rate of development of these marks.     

The effectiveness of strong afterglow phosphor powder in the detection of fingermarks

There are numerous types of fluorescent fingermark powders or reagents used with the visualization of latent fingermarks deposited on multicolored substrate surfaces that can present a contrast problem if developed with regular fingermark powders. The developed fingermarks can show bright fluorescence upon exposure to laser, ultraviolet light and other light sources. These kinds of methods share a common concern, where surfaces and other substrates may fluoresce also. To overcome this concern, we have developed a phosphor powder which offers a strong afterglow effect which aid in the establishment of better fingermark detection. With the advent of a phosphor powder no special devices are required and the results obtained from fresh or a few days aged latent fingermarks left on: non-porous; semi-porous and also on some porous surfaces have been good. The strong afterglow effect offered by phosphor powder is also applicable for cyanoacrylate fumed fingermarks. Lift off and photography procedures of the developed fingermarks are incorporated in this paper.     

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.     

Evaluation of a Hot Print System for the development of latent fingermarks on thermal paper: A pseudo-operational trial

Enhancement of latent fingermarks on thermal paper poses a number of problems when using traditional methods used for porous substrates due to blackening of the thermal layer as a result of polar solvents present within the reagents and high temperatures oxidising the acid/dye complex. Thus, methods which prevent such reactions are favoured for the development of latent prints on said substrates. A comparative pseudo-operational trial using UV, Hot Print System (HPS), ninhydrin and ThermaNIN was performed on 1000 thermal paper substrates gathered from various sources. The results indicated that the most effective method was an acetone pre-wash followed by ninhydrin. The sequence of HPS-ninhydrin was similarly effective when compared to ninhydrin as a sole technique. ThermaNIN produced fewer marks than ninhydrin but was superior to HPS. Whilst the HPS developed some fingermarks, there was only a very small number of marks uniquely developed by it.     

Inherent Fluorescence Detection of Latent Fingermarks by Homemade Shortwave Ultraviolet Laser

Detection of latent fingermarks on various substrates is critical in crime investigations. Conventional chemical methods using reagents could contaminate or even destruct biological information of samples. Here, an optical method and successful case application of detecting latent fingermarks through long‐wave ultraviolet (UV) fluorescence (300–400 nm) by shortwave UV laser excitation is reported. Experimental results indicate that the recovery rate of the latent fingermarks on various paper items is in the range of 70–80% without chemical treatments. Moreover, the optical method allows for the preservation of samples for further examination, such as polymerase chain reaction (PCR) testing. The technique has also been successfully applied to a criminal case in identifying the suspect, which, to the best of our knowledge, has never been reported in real crime investigations. Therefore, such a method as UV‐excited UV fluorescence in detecting latent fingermarks may be better for examination in cases where biological information of samples is needed for consequent testing.     

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.     

Photoluminescence of blood by acidic hydrogen peroxide—A preliminary test

In this study, the authors found that treating blood with 1 M HCl and 2% (w/v) 5-sulfosalicylic acid (SSA) in 1% (v/v) hydrogen peroxide mixture can produce photoluminescence of blood. SSA was added as a blood fixer. The photoluminescence was induced by irradiation of a forensic light source at 505 nm, which was detected using a 550 nm barrier filter. In this experiment, various level of acid and hydrogen peroxide were tested to find the optimal formulation of reagents, spot tests were conducted with diluted blood to test the sensitivity of this reagent, and impressions in blood left on porous/nonporous surfaces were enhanced. The sensitivity of this solution was slightly lower than Bluestar and was similar to leucocrystal violet or leucomalachite green on both porous/non-porous surfaces. The photoluminescence of blood treated with this reagent has been observed over 2 months. Using this reagent, it was possible to observe fingermarks or footwear impressions in blood on a black porous/non-porous surface. Through this, it was found that using this reagent could enhance bloodstains regardless of the porosity or color of the surface.     

Studies into exfoliation and coating of Egyptian blue in methanol for application to the detection of latent fingermarks

We have recently demonstrated that coated exfoliated Egyptian blue powder is effective for detecting latent fingermarks on a range of highly-patterned non-porous and semi-porous surfaces. In this extension of that work, we present our studies into an alternative approach to prepare exfoliated Egyptian blue coated with cetrimonium bromide and Tween® 20 using a simpler technique. The quality of the latent fingermarks developed with these exfoliated powders and the commercial powder were compared in a comprehensive study. Depletion series of natural fingermarks from a wide range of donors (12 males and females) deposited on non-porous (glass slides) and semi-porous (Australian banknotes) surfaces were used in this study. Enhancement in the performance of the coated exfoliated particles compared to the commercial powder was observed, particularly in the case of aged fingermarks and polymer banknotes as challenging substrates.     

Fingermark detection on non-porous and semi-porous surfaces using NaYF4:Er,Yb up-converter particles

This article describes the first use of an anti-Stokes material, or up-converter, for the development of latent fingermarks on a range of non-porous surfaces. Anti-Stokes materials can absorb long-wavelength light and emit light at a shorter wavelength. This property is unusual in both natural and artificial materials and so fingermark detection techniques based on anti-Stokes luminescence are potentially sensitive and selective. Latent fingermarks on luminescent and non-luminescent substrates, including Australian polymer banknotes (a well-known 'difficult' surface), were developed with sodium yttrium tetrafluoride doped with erbium and ytterbium (NaYF(4):Er,Yb) by dry powder, wet powder, and cyanoacrylate staining techniques. This study illustrates the potential of up-converter phosphors for the detection of latent fingermarks.     

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.     

Latent fingermark development on a range of porous substrates using ninhydrin analogs--a comparison with ninhydrin and 1,8-diazofluoren

Three relatively new reagents for developing latent fingermarks on porous substrates, 1,2-indandione (IND), 5-methylthioninhydrin (5-MTN), and lawsone, are compared with the more widely used ninhydrin and 1,8-diazofluoren (DFO). Developed latent fingermark visualization on 10 different substrates comprising colored papers, cardboard, and cellophane rather than conventional printer and writing/notepad paper is assessed using latent fingermark deposits from 48 donors. Results show improved fluorescent fingermark visualization using IND compared with DFO on a range of colored cardboards and thick white paper, thus extending the range of substrates known to yield improved visualization with IND. Adding zinc chloride to IND failed to yield any further improvement in fluorescent fingermark visualization. 5-MTN (with and without zinc chloride posttreatment) showed no improvement in visualization compared with ninhydrin and DFO although visible fingermarks were developed. Lawsone produced fluorescent visible fingermarks only with white substrates, which were inferior to those produced with DFO.     

Methods for the enhancement of fingermarks in blood

Fingermarks formed in or by blood often require specific development techniques. This review examines techniques and materials that may be used to enhance and record fingermarks deposited in blood or fingermarks generated by blood-contaminated papillary ridges. A large number of techniques are presented here and are discussed from a chemical as well as practical perspective. It is concluded that an optimized sequence of techniques targeting both latent (non-bloody) and bloody fingermarks must be applied to detect and enhance the maximum number of marks, and therefore optimize the information content from exhibits that may bear marks in blood.     

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.     

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.     

Can latent fingerprint disclose the sex of the donor? A preliminary test study using GC–MS analysis of latent fingerprints

While fingerprints are a highly used means of identification, not every fingerprint left behind on a potential crime scene can be used for identification purposes. In some cases, the fingerprint may be smudged, partially preserved or overlapping with other prints hence distorting the ridge pattern and may therefore be not appropriate for identification. Further, fingermark residue yields a very low abundance of genetic material for DNA analysis. In such cases, the fingermark may be used to retrieve basic donor information such as sex. The focus of this paper was to assess the possibility of differentiating between the sexes of the donor of latent fingermarks. Analytical method was GC–MS analysis of the chemical compounds of latent fingermarks using 22 male and 22 female donors. Results showed 44 identified compounds. Two alcohols, octadecanol C₁₈ and eicosanol C₂₀, were found to show a difference that was statistically significant between male and female donors. There is also some evidence for the possibility of distinguishing sex of the fingermark donor based on the distribution of branched chain fatty acids, as free compounds or esterified in wax esters.     

Exploring the recovery and detection of messenger RNA and DNA from enhanced fingermarks in blood

Often in the examination of bloodstained fingermarks discussion occurs around whether to prioritise the fingerprint evidence or focus on the biological evidence. Collecting a sample for genetic profiling may result in the loss of ridge detail that could have been used for fingerprint comparison. Fingermark enhancement and recovery methods along with sample collection methods could also compromise downstream genetic analysis. Previous forensic casework has highlighted circumstances where, after enhancement had been performed, it would have been extremely valuable to both identify the body fluid and generate a DNA profile from the same sample.We enhanced depletion series of fingermarks made in blood, using single treatments consisting of aqueous amido black, methanol-based amido black, acid yellow and leucocrystal violet, and exposure to long wave UV light. We then extracted the DNA and RNA for profiling, to assess the recovery and detection of genetic material from the enhanced fingermarks.We have shown that genetic profiling of bloodstained fingermarks can be successful after chemical enhancement; however it may still be necessary to prioritise evidence types in certain circumstances. From our results it appears that even with visible bloodstained fingermarks, leucocrystal violet can reduce the effectiveness of subsequent messenger RNA profiling. Aqueous amido black and acid yellow also have adverse effects on messenger RNA profiling of depleted fingermarks with low levels of cellular material. These results help with forensic decision-making by expanding knowledge of the extent of the detrimental effects of blood-enhancement reagents on both DNA profiling and body fluid identification using messenger RNA profiling.