A proteomic approach for the rapid, multi-informative and reliable identification of blood

Blood evidence is frequently encountered at the scene of violent crimes and can provide valuable intelligence in the forensic investigation of serious offences. Because many of the current enhancement methods used by crime scene investigators are presumptive, the visualisation of blood is not always reliable nor does it bear additional information. In the work presented here, two methods employing a shotgun bottom up proteomic approach for the detection of blood are reported; the developed protocols employ both an in solution digestion method and a recently proposed procedure involving immobilization of trypsin on hydrophobin Vmh2 coated MALDI sample plate. The methods are complementary as whilst one yields more identifiable proteins (as biomolecular signatures), the other is extremely rapid (5 minutes). Additionally, data demonstrate the opportunity to discriminate blood provenance even when two different blood sources are present in a mixture. This approach is also suitable for old bloodstains which had been previously chemically enhanced, as experiments conducted on a 9-year-old bloodstain deposited on a ceramic tile demonstrate

Evaluation of a 1,2-indanedione formulation containing zinc chloride for improved fingermark detection on paper

1,2-Indanedione was first proposed as an amino acid reagent for latent fingermark detection in 1997. Since that time, research groups around the world have undertaken and reported on studies aimed at optimizing the technique and comparing the results obtained with both ninhydrin and DFO development. There has been no general consensus in terms of preferred formulation, development conditions, metal salt treatment, observation conditions, and relative performance compared to conventional techniques. In this study, a new indanedione-zinc formulation is proposed that provides improved detection capabilities compared to DFO, with results that are less dependent on the relative moisture content of treated fingermarks

Vacuum metal deposition: Developing latent fingerprints on polyethylene substrates after the deposition of excess gold

A previously identified difficulty with the development of latent fingerprints on low-density polyethylene (LDPE) by vacuum metal deposition (VMD) is that excess gold deposition prevents effective zinc deposition and so inhibits latent print development [1]. The investigation of a means to correct for excess gold deposition was the basis for this study. Exposure to zinc and the readmission of air into the vacuum chamber followed by VMD development results in the deactivation of the initial gold clusters due to the formation of zinc oxide and the adsorption of air and water molecules. As a result, the majority of the gold deposited during the second treatment creates new gold clusters rather than adding to the gold clusters previously formed. After excess gold deposition on LDPE, the deposition of 1.5 times the optimum gold amount will result in good-quality normal development. The results also indicate that, on all surfaces, at least twice the initial gold count should be used for re-treatment when further development is required after air has been readmitted to the chamber. © 2001 Elsevier Science Ireland Ltd. All rights reserved

Vacuum metal deposition: Factors affecting normal and reverse development of latent fingerprints on polyethylene substrates

Vacuum metal deposition (VMD) is an established technique for the development of latent fingerprints on non-porous surfaces. VMD has advantages over cyanoacrylate fuming, especially in circumstances where prints are old, have been exposed to adverse environmental conditions, or are present on semi-porous surfaces. Under normal circumstances, VMD produces 'negative' prints as zinc deposits onto the background substrate and not the print ridges themselves. A phenomenon of 'reverse' development, when zinc deposits onto the print ridges and not the background, has been reported by many authors but its causes have not been conclusively identified. Four plastic substrates were used in this study and these could be easily divided into two groups based on the types of development observed as the amount of deposited gold was increased. On group I plastics, identified as low-density polyethylene (LDPE), normal development then reverse development and finally no development resulted with increasing gold. On group II plastics, identified as high-density polyethylene (HDPE), normal development then over-development and finally poor-quality normal development resulted with increasing gold. Our results suggest that the difference between these plastic types causes variations in the gold film structure which in turn dictates the nature of the zinc deposition. On group I plastics, the structure and thickness of the gold film has been identified as the critical factor in the occurrence of normal or reverse development. Thin gold films on plastic substrates form small 'clusters' (or agglomerates) rather than the atoms being uniformly spread over the surface. The size and shape of these clusters is critical. Once the clusters reach a certain morphology, they no longer act as nucleation sites for zinc, and hence, zinc will not deposit onto the substrate. On group II plastics, results suggest that the gold clusters are smaller and more densely packed. Hence, even though the same amount of gold has been deposited, the gold clusters in this case do not reach the critical morphology and so continue to act as nucleation sites for zinc. Typically, zinc will not deposit onto the fingerprint ridges as the gold nucleation sites are buried within the print residue. However, when more gold is deposited, gold emerges at the surface of the latent print allowing zinc deposition onto the ridges. The rate of gold evaporation was found not to affect the structure of the gold film, although a slower rate of evaporation resulted in more effective deposition. (C) 2000 Elsevier Science Ireland Ltd

Evaluation of 5-Methylthioninhydrin for the Detection of Fingermarks on Porous Surfaces and Comparison

The chemical 5-methylthioninhydrin was developed in the early 1990s for treating fingermarks on porous surfaces. Although many researchers showed the promise of this chemical during the years between 1990 and 1997, current research indicates that this reagent is sill not commonly used in casework. The current study assessed the commercially produced 5-methylthioninhydrin and compared it to the more commonly used reagents for detecting fingermarks on porous surfaces. The study found that 5-methylthioninhydrin is superior to ninhydrin; however, 1,2-indanedione produced a much stronger luminescence when used to treat latent fingermarks. Comparable fluorescence was produced with 5-methlthioninhydrin after metal salt treatment to DFO; the high background detracts from the ridge detail, however. The study concludes that although the cost of 5-methylthioninhydrin is higher than for conventional reagents, its use may be justified in some circumstances. The second article begins with an illustrated step-by-step demonstration of the technique for blending two exposures of the same scene. It involves the use of layers within Adobe Photoshop CS and then placing one exposure overtop of another exposure. The best qualities of each exposure are then used in the final print. The article then examines a few applied forensic applications of the blending of two exposures, including a technique for rescuing underexposed images. This issues section on Society Business (Canadian Identification Society) addresses Society awards, the Presidents message," the 29th CIS Educational Conference, guidelines for authors, a listing of award winners and past presidents, and a listing of staff member

An evaluation of multimetal deposition II

Multimetal deposition (MMD) has not found routine application because of its complexity and inconsistent results. Recent research that sought to overcome these problems resulted in the development of a new formulation known as MMDII. MMDII utilizes smaller colloidal gold particles (14 nm as compared to 30 nm) and an alternative physical developer (silver acetate/hydroquinone rather than silver nitrate/iron(II)/iron(III)). Several MMD formulations were evaluated in this study, and MMDII proved to be the superior formulation, giving better overall print detail. On nonporous surfaces, MMDII may offer further print development than that achieved with cyanoacrylate fuming (CA) and luminescent staining, but vacuum metal deposition (VMD) always gave superior results to MMD. MMDII and VMD were compared to standard techniques on a number of semiporous surfaces, including expanded polystyrene, waxed paper, latex gloves, and nitrile gloves. MMDII proved to be the technique of choice on these surfaces. The ability of MMDII to react with print residue within and on the surface is believed to be important to its success

The development of latent fingerprints on polymer banknotes

Polymer banknotes, especially older banknotes and banknotes with aged prints, present challenges for latent print development. A sequence of techniques has been optimized for the development of aged prints on the surface of banknotes. The procedure involves optical examination, cyanoacrylate fuming, vacuum metal deposition treatment, and luminescence staining. It is essential to treat banknotes with cyanoacrylate fuming as soon as they are received so that the print degradation, which occurs quickly on the banknote surface, is minimized. Vacuum metal deposition treatment should also be applied as soon as possible after cyanoacrylate fuming. Treatments other than those outlined in this procedure should be avoided, because they will be detrimental to vacuum metal deposition development

Optimisation and evaluation of 1,2-indanedione for use as a fingermark reagent and its application to real samples

1,2-Indanedione is an emerging fingermark reagent used on porous surfaces. The general consensus is that this reagent is at least as sensitive as DFO, with some research showing higher sensitivity for 1,2-indanedione as opposed to DFO. However, a number of discrepancies existed in the literature as to which formulation and which development procedure produces optimal results. This project set out to investigate the best formulation and development procedure under Australian conditions, encompassing all published recommendations as well as some novel approaches. 1,2-Indanedione formulations were compared with respect to initial colour, fluorescence, concentration of reagent, acetic acid concentration, and the effect of different carrier solvents. Numerous development conditions were investigated, including a conventional oven, a heat press and humidity. Further enhancement using metal salt treatment and liquid nitrogen was also evaluated. The heat press set at 165 °C for 10 s proved to give the best initial colour and most intense luminescence. Secondary metal salt treatment improved initial colour and luminescence. The Polilight, the VSC 2000, and the Condor Chemical Imaging macroscope have been used to detect the fingerprints developed with 1,2-indanedione on a variety of high- and low-quality porous and semi-porous surfaces, with impressive results overall. Laboratory and field tests were conducted to compare 1,2-indanedione with DFO and ninhydrin as well as to investigate the position of 1,2-indanedione in the sequence of reagents for fingermark detection on porous surfaces. Overall, 1,2-indanedione proved to be a viable alternative to traditional methods for the detection of fingermarks on porous surfaces, with more fingermarks being developed using this reagent on real samples than both DFO and ninhydrin and a combination of the two reagents. © 2006

Use of dichloromethane in fingerprint reagent formulations

Letter to the edito