Xanthe Spindler

Chadwick, S.R., Maynard, P.J., Kirkbride, K.P., Lennard, C.J., McDonagh, A.M., Spindler, X. & Roux, C.P. 2012, 'Styryl dye coated metal oxide powders for the detection of latent fingermarks on non-porous surfaces', Forensic Science International, vol. 219, no. 1-3, pp. 208-214.
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Conventional fingermark powders rely on contrast induced by absorption/reflection (e.g. black powder) or luminescence in the visible region (e.g. Blitz Green-«). In most cases, these powders provide sufficient contrast; however, in some circumstances surface characteristics can interfere with the visualisation of powdered fingermarks. Visualisation in the near infra-red (NIR) region, however, has been shown to eliminate interferences commonly encountered in the visible region. In this study, a mixture of rhodamine 6G and the NIR laser dye styryl 11 (STaR 11) was coated onto an aluminium oxide nanopowder and then mixed with silver magnetic powder to develop and visualise fingermarks in the NIR. When compared to Blitz Green-«, it was determined that the STaR 11 magnetic powder was better suited for marks deposited on textured surfaces and for older marks, whereas Blitz Green-« performed better on smooth glossy surfaces. The ability of the STaR 11 mixed dye formulation to be visualised in both the visible and NIR regions also provides a significant advantage over conventional luminescent fingermark powders.

Montgomery, L.N., Spindler, X., Maynard, P.J., Lennard, C.J. & Roux, C.P. 2012, 'Pre-treatment strategies for the improved cyanoacrylate development of dry latent fingermarks on non-porous surfaces', Journal of Forensic Identification, vol. 62, no. 5, pp. 517-542.
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Cyanoacrylate fuming is a popular technique commonly used by evidence examiners for the development of latent fingermarks on nonporous surfaces. The process involves the preferential formation of hard, white polycyanoacrylate along the ridgelines of the fingerprint as opposed to the substrate background. This preferential deposition results in contrast between the fingerprint and substrate. This contrast may be further enhanced through the use of staining techniques such as rhodamine 6G. Because the cyanoacrylate mechanism is believed to be initiated by fingerprint constituents and catalyzed by moisture, ii follows that fingerprints subjected to harsh conditions (e.g., heat, low humidity, or CV light) often produce poorly developed results. This study aimed to further investigate and validate the use of 10% w/v methylamine as a pretreatment strategy to overcome the limitations associated with the cyanoacrylate development of dry fingerprints and to compare the results with those obtained using previously proposed pretreatment solutions. The effectiveness of this treatment was demonstrated on samples similar to those encountered in casework, and scanning electron microscopy (SEM) of the treated fingerprints con- firmed the rejuvenation of the dry latent deposits through a qualitative assessment of the polymer morphology.

Wood, M., Maynard, P.J., Spindler, X., Lennard, C.J. & Roux, C.P. 2012, 'Visualization of latent fingermarks using an aptamer-based reagent', Angewandte Chemie International Edition, vol. 124, no. 0, pp. 12438-12440.
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Don't touch! Aptamers selected against lysozyme are transformed into aptamer-based reagents, with which latent fingermarks can be developed with high selectivity and sensitivity. The design of aptamers targeting components of latent fingermarks opens up a new range of detection methods that previously have not been explored.

Chadwick, S.R., Maynard, P.J., Kirkbride, K.P., Lennard, C.J., Spindler, X. & Roux, C.P. 2011, 'Use of Styryl 11 and STaR 11 for the luminescence enhancement of cyanoacrylate-developed fingermarks in the visible and near-infrared regions', Journal of Forensic Sciences, vol. 56, no. 6, pp. 1505-1513.
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In current casework, most post-cyanoacrylate stains rely on luminescence emission in the visible region (400-700 nm). While traditional stains such as rhodamine 6G work well under most circumstances, some surfaces may generate background luminescence under the same conditions. Detection in the near-infrared region (NIR > 700 nm) has shown to be effective in minimizing the interferences from such surfaces. The laser dye styryl 11 generated strongly luminescent fingermarks when applied after cyanoacrylate fuming on all surfaces tested. When compared to rhodamine 6G, the dye was superior only when viewed in the NIR. Styryl 11 was subsequently combined with rhodamine 6G, and the mixed stain formulation (named StaR 11 by the authors) induced stronger luminescence compared with styryl 11 alone with an ability to visualize in both the visible and NIR regions. Reliable and consistent results were obtained when using either styryl 11 alone or the STaR 11 mixture. The enhancement achieved did not otherwise vary depending on the source of the fingermark secretions. With visualization possible in both the visible and NIR regions, the styryl 11/rhodamine 6G mixture showed significant potential as a post-cyanoacrylate stain.

Fung, T.C., Grimwood, K.M., Shimmon, R., Spindler, X., Maynard, P.J., Lennard, C.J. & Roux, C.P. 2011, 'Investigation of hydrogen cyanide generation from the cyanoacrylate fuming process used for latent fingermark detection', Forensic Science International, vol. 212, no. 1-3, pp. 143-149.
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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. 13C 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 8C. Using an optimised picrate+resorcinol method, it was shown that around 10 mg of HCN could be generated from the heating of 1 g of cyanoacrylate monomer at 200 8C. For one of the adhesives tested, this increased to above 100 mg of HCN when 1 g of cyanoacrylate monomer was heated at 280 8C. Recommendations are provided that, if followed, should ensure that the cyanoacrylate fuming process can be safely applied with minimal risk to the operator.

Spindler, X., Hofstetter, O., McDonagh, A.M., Roux, C.P. & Lennard, C.J. 2011, 'Enhancement of latent fingermarks on non-porous surfaces using anti-l-amino acid antibodies conjugated to gold nanoparticles', Chemical Communications, vol. 47, no. 19, pp. 5602-5604.
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Enantioselective anti-L-amino acid antibodies conjugated to gold nanoparticles are shown to facilitate the detection of latent fingermarks by interacting with amino acids present in friction ridge secretions. This antibody-based system is particularly effective for the enhancement of aged and dried fingermarks on non-porous surfaces, an area unexploited by current techniques.

Spindler, X., Shimmon, R., Roux, C.P. & Lennard, C.J. 2011, 'The effect of zinc chloride, humidity and the substrate on the reaction of 1,2-indanedione-zinc with amino acids in latent fingermark secretions', Forensic Science International, vol. 212, no. 1-3, pp. 150-157.
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Anecdotal evidence from forensic practitioners and studies conducted under controlled conditions have indicated that the reaction between 1,2-indanedione and the amino acids present in latent fingermark deposits is highly susceptible to ambient humidity. The addition of catalytic amounts of zinc chloride to the 1,2-indanedione working solution + usually in the order of 1:25 to 1:4 molar ratio (indanedione:zinc) + significantly improves the colour and luminescence of fingermarks treated under dry conditions but appears to have a negligible effect on fingermarks treated in humid environments. The results presented in this paper confirmed that zinc(II) ions added to the 1,2-indanedione working solution act as a Lewis acid catalyst, stabilising a key intermediate during a rate-limiting hydrolysis step. Furthermore, studying the reaction using a chromatography-grade cellulose substrate method previously reported confirmed that cellulose substrates play a major role in facilitating the indanedione-amino acid reaction by acting as a surface catalyst in the early stages of the reaction and by directing the formation of the desired luminescent product (Joullie¦ +s Pink).

Chan, J.H., Shimmon, R., Spindler, X., Maynard, P.J., Lennard, C.J., Roux, C.P., Stuart, B.H. 2010, 'An investigation of isatin as a potential reagent for latent fingermark detection on porous surfaces', Journal of Forensic Identification, vol. 60, no. 3, pp. 320-336.
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This study investigated isatin as a potential fingermark enhancement reagent for use on porous surfaces. A number of parameters were investigated, including concentration, solvent system, pH of the solution, and optimization of the development conditions. It was determined that isatin at a concentration of 0.05% (w/v) provided the optimum balance between the luminescence of the fingermark ridges and background. A carrier solvent of dioxane mixed with acetone [12.5% (v/v)] produced the most intense luminescence. It was determined that the optimum pH for the development of fingermarks was 5.0 and that this could be reached by the addition of 4% (vlv) sodium carbonate buffer. The use of a dry heat press at 180¦C for 10 s provided optimal development conditions.