Back to Amido Black: Uncovering touch DNA in blood-contaminated fingermarks.

Blood-contaminated fingermarks (FMs) found in violent crime scenes may directly connect the suspect to the crime by linking the FM to the suspect and the DNA from the blood to the victim. However, marks that are incomparable are considered "dead-evidence" as the link to the suspect is lost. In this study, a novel approach was attempted to uncover the trace amount of touch DNA of the suspect in such marks. We examined the effect of two enhancement methods, ninhydrin (NIN) and amido black (AB), on DNA recovery from blood-contaminated FMs. A total of 108 fingerprints were deposited in three sets of depleted blood prints, blood-contaminated FMs, and latent FMs. All FMs were developed by either NIN or AB, or left undeveloped as reference followed by the quantification of the total DNA amount. This work shows that while AB had a detrimental effect on the quantity of blood-derived DNA specifically, reducing it by half, no similar effect was observed for touch DNA in latent FMs. This reduction led to the alteration of the major-to-minor DNA profile ratio to 70:30, thus enabling to obtain two distinct DNA profiles of the suspect from the touch DNA as well as the victim's profile from the blood. From an operational perspective, the use of AB in crime scenes may have an added value to retrieve the crucial DNA profile of the suspect, thus resurrecting a "dead-evidence."

"MALDI-CSI": A proposed method for the tandem detection of human blood and DNA typing from enhanced fingermarks.

Matrix Assisted Laser Desorption Ionization Mass Spectrometry Profiling and Imaging (MALDI MSP and MALDI MSI), in combination with bottom up proteomics, have proven to successfully detect and map blood-derived peptide signatures in blood fingermarks, with high specificity and compatibility with a number of blood enhancement techniques (BET). In the present study, the application of MALDI MSP and MSI to blood marks has been investigated further. In particular, the MALDI based detection and visualisation of blood has been explored in tandem with DNA typing. This investigation has been undertaken in a scenario simulating blood fingermarks on painted walls. In the present study, two sets of marks were analysed with each set comprising of a depletion series of four marks deposited on a surface treated to simulate painted walls: Set I - developed with Ninhydrin (NIN) and Set II- developed with Acid Black-1 (AB-1). For both sets, the application of MALDI MSP was successful in detecting haem and human specific haemoglobin peptide markers. MALDI MSI also provided molecular images by visualising haem on the ridge pattern enhanced by BET. The feasibility of successful and subsequent DNA profiling from the recovered fingermarks was also assessed for marks that had undergone enzymatic in situ digestion and MALDI MSI; it was observed that in 73% of the samples analysed, a DNA profile suitable for comparison was obtained. Based on these results, a possible operational workflow has been proposed incorporating the use of a MALDI MS based approach as a confirmatory test for human blood enabling subsequent DNA typing.

Time is Money or Money is Time? A Rapid Operational Sequence for Detecting Fingermarks on Polymer Banknotes.

Banknotes are often found in high-profile crimes such as armed robberies, bribery, and terrorist activity. However, such exhibits present a challenge to forensic operatives regarding fingermarks development, due to their mass quantities, potential for fingermarks on both sides, and their unique complex background in terms of color, irregular patterns, and topography. Hence, the standard development protocols become inefficient, due to the difficulty in achieving high contrast images over the background. This study focused on finding an operational sequence that would minimize the time of work on polymer banknotes, in terms of both development and image processing. Thirty-two fingermarks were developed by vacuum metal deposition (VMD), black magnetic powder, and cyanoacrylate fuming (CA) followed by visualization and imaging by reflected short-wave UV (RUVIS) (96 in total), showing a distinct advantage to the CA and RUVIS imaging over the other two techniques with a 75% success rate in the dark and high background regions, due to its physical principle which neutralizes high background interference. The images were then scanned by the automatic fingerprint identification system (AFIS) to test its ability to correctly differentiate false background features from real ones, again, showing a superiority of the RUVIS with 63% of the total initial marked features, being real. Overall, the CA and RUVIS sequence was found to be an ultimate method for multiple, same-type surfaces, with the RUVIS capable of visualization and capturing of the images simultaneously, significantly reducing the time of development and image processing.

An efficient and eco-friendly workflow for dual fingermark processing and STR profiling.

Since its discovery in 1997, DNA retrieved from touched or handled items (touch DNA) has been increasingly used in criminal casework. Depending on the nature of the substrate examined, numerous techniques are being used for fingermark (FM) collection and development, however, it has been shown that FM processing may impede or even prevent the dual analysis of FMs and DNA. In search for a possible solution, we have recently established a novel workflow for a non-destructive collection and eco-friendly visualization of latent FMs using white BVDA gel-lifters and black Wetwop® solution. In the present study, the scope and limitations of the proposed protocol were thoroughly examined for DNA recovery and genotyping in relation to substrate type (porous and non-porous), time elapsed after the deposition (1, 7 and 14 days) and donor's gender. The study included 120 developed FMs of 20 donors (10 males and 10 females, aged 25-50 years), from which 240 DNA samples were recovered and quantified. The independent analysis of two DNA samples recovered from each FM, one - from the adhesive surface of the gel-lifter and the other - from its imprint on the protecting acetate cover, allowed us not only to increase the total number of the identified donors, but also to achieve a higher level of confidence per FM. Though this approach appeared to be more efficient on non-porous substrates (up to 65% on car tin), it is noteworthy that forensically useful DNA profiles (with at least 8 full STR loci) were generated from poor-quality FMs on the porous substrate, drywall (25% and 15% in males and females, respectively). Finally, the integration of the results of touch DNA analysis and that of FM visual inspection allowed us to increase by more than half the number of personal identifications and to strengthen the chain of forensic evidence.

Selective Binding and Precipitation of Cesium Ions from Aqueous Solutions: A Size-Driven Supramolecular Reaction.

The nuclear disasters of Chernobyl and Fukushima presented an urgent need for finding solutions to treatment of radioactive wastes. Among the by-products of nuclear fission is radioactive 137 Cs, which evokes an environmental hazard due to its long half-life (>30 years) and high solubility in water. In this work, a water-soluble organic ligand, readily obtained from alloxan and 1,3,5-benzenetriol, has been found to selectively bind and precipitate Cs+ ions from aqueous solutions. The special rigid structure of the ligand, which consists of a "tripodal" carbonyl base above and below an aromatic plane, contributes to the size-driven selectivity towards the large Cs+ ions and the formation of a giant, insoluble supramolecular complex. In addition to the low costs of the ligand, high yields and effectiveness in precipitating Cs+ ions, the Cs-complex revealed a high endurance to continuous doses of γ-radiation, increasing its potential to act as a precipitating agent for 137 Cs.

Development of fingermarks on Latex gloves: The solution to a challenging surface.

Used Latex gloves found at crime scenes can provide strong evidence against a suspect as they almost certainly contain both the fingermarks and DNA of the perpetrator who had worn them. However, over the years, Latex gloves have proved to be a rather difficult substrate for fingermarks development, with most of the standard techniques producing poor results. In this study, the two main protocols for development on either porous or non-porous surfaces: Ninhydrin-HFE and superglue fuming followed by crystal violet (CV) dyeing, respectively, had been examined on 100 disposable Latex gloves from twenty five donors. The results distinctly showed a high superiority of Ninhydrin-HFE over the superglue fuming indicating the porous rather than the non-porous properties of the interior of the gloves. Yet, not all the usual ninhydrin development formulations yielded the desirable results, leading to the conclusion that the success of development rests on the solvent-sensitive structure of the gloves. As natural latex contains contaminant proteins, that were found to cause allergic reactions in different people, the manufacturing of disposable gloves had been altered over the years to prevent contact with these proteins by adding an intrinsic polymer-coating. Thus, it was essential to use an inert solvent system that should keep the interior polymer-coating intact, allowing a reaction only with the amino acids on the surface rather than the latex proteins in the glove. The SEM analyses showed that HFE-7100 as opposed to petroleum ether, does not harm the inner coating, hence, providing the ideal solution to this challenging surface.

Crystal structure of (acetato-κO)(ethanol-κO)[(9S,17S,21S,29S)-9,17,21,29-tetra-hydroxy-18,30-dioxa-octa-cyclo-[18.10.0.0(2,7).0(8,19).0(9,17).0(11,16).0(21,29).0(23,28)]triaconta-1,3,5,7,11(16),12,14,19,23(28),24,26-undeca-ene-10,22-dione-κ(3) O (18),O (21),O (22)]caesium ethanol monosolvate.

The title compound, [Cs(CH3COO)(C28H16O8)(C2H5OH)]·C2H5OH, is the product of the complexation between one vasarene analogue [1], bis ninhydrin naphthalene-1,3-diol and CsF, where the F(-) ion has reacted with residual acetic acid (AcOH), to form a [1]·CsOAc complex. The inter-molecular inter-actions with the multiple oxygen-containing functional groups of the ligand, as well as O-H⋯O hydrogen bonds involving the ethanol solvent mol-ecules, stabilize the complex, forming a chain along [100]. Additional parallel-displaced π-π stacking, with an inter-planar distance of 3.669 (1) Å, connect several unit cells in a three-dimensional supra-molecular structure, though, the larger size of AcO(-) (1.60 Å) compared to F(-) (1.33 Å) prevents the tight packing that was once achieved with other vasarene complexes of CsF.

Bis(benzyl-tri-methyl-ammonium) bis-[(4SR,12SR,18RS,26RS)-4,18,26-trihy-droxy-12-oxido-13,17-dioxahepta-cyclo-[14.10.0.0(3,14).0(4,12).0(6,11).0(18,26).0(19,24)]hexa-cosa-1,3(14),6,8,10,15,19,21,23-nona-ene-5,25-dione] sesquihydrate: dimeric structure formation via [O-H-O](-) negative charge-assisted hydrogen bonds (-CAHB) with benzyl-tri-methyl-ammonium counter-ions.

The reaction between bis-ninhydrin resorcinol and benzyl-tri-methyl-ammonium fluoride in ethanol has produced the title compound, 2C10H16N(+)·2C24H13O8 (-)·1.5H2O, which contains a unique centrosymmetric supra-molecular dimeric entity, where two deprotonated ligands are held together via two strong and short [O⋯O = 2.4395 (13) Å] [O-H-O](-) bonds of the type negative charge-assisted hydrogen bonds (-CAHB). The central aromatic rings of the ligands create parallel-displaced π-π stacking at an inter-planar distance of 3.381 (1) Å, which helps stabilize the dimer. In the crystal, two symmetry-related solvent water mol-ecules with a site occupancy of 0.75 are attached to the carbonyl groups of the dimer by weaker O-H⋯O hydrogen bonds, forming chains along [101].