The effect of the anti-coagulant EDTA on the deposition and adhesion of whole blood deposits on non-porous substrates.

An investigation into whether the addition of a commonly used anti-coagulant agent like ethylenediaminetetraacetic acid (EDTA) has an impact on the adhesion potential of blood to non-porous substrates was conducted. Two non-porous substrates (aluminum and polypropylene) exhibiting six different surface roughness categories (R1-R6) were used as test substrates upon which either whole blood or blood treated with EDTA was deposited. Samples were exposed to different drying periods (24 hours, 48 hours, and 1 week) before undergoing a tapping agitation experiment in order to evaluate the adhesion to the surface.

The impact of substrate characteristics on the collection and persistence of biological materials, and their implications for forensic casework.

This study assessed the level of nucleic acid persistence on the substrate pre-, and post-swabbing, in order to assess whether biological materials (touch, saliva, semen, and blood) are collected differently depending on the substrate characteristics. A total of 48 samples per deposit and substrate variety (n = 384) were assessed by tracking the persistence of nucleic acid using Diamond™ Nucleic Acid Dye (DD) staining and Polilight photography. The number of DD nucleic acid fluorescent complexes formed post-staining were counted (fluorescent count) and in conjunction with the fluorescence signal intensity (DD nucleic acid complex accumulation) used to estimate the level of nucleic acid persistence on substrates.

How the physicochemical substrate properties can influence the deposition of blood and seminal deposits.

A comprehensive investigation into the impact of the physical and chemical variables of a substrate on the deposition was conducted to aid in the estimation of the subsequent transfer probabilities of blood and semen. The study focussed on surface roughness, topography, surface free energy (SFE), wettability, and the capacity for protein adsorption. Conjointly, evaluations of the physical and chemical characteristics of blood and seminal deposits were conducted, to assess the fluid dynamics of these non-Newtonian fluids and their adhesion potential to aluminium and polypropylene.

Touch DNA recovery from unfired and fired cartridges: Comparison of swabbing, tape lifting and soaking.

Over the recent few years, several DNA collection techniques and methodologies have been published for the recovery of DNA from fired cartridge cases. In this study, swabbing, the DNA collection technique currently used in our jurisdiction (NSW, Australia), was compared with tape lifting and soaking to assess DNA recovery rates, DNA quality and profile quality. Brass .

"Technical Note:" Optimisation of Diamond™ Nucleic Acid Dye preparation, application, and visualisation, for latent DNA detection.

A targeted sampling approach of latent DNA, deposited when a person makes contact with a surface, can prove challenging during crime scene or evidence processing, with the sampling of latent DNA often relying on the expert judgement from crime scene officers and forensic examiners. As such, the ability to use the quick and robust screening tool Diamond™ Nucleic Acid Dye (DD) was explored, with a focus on the visualisation of latent DNA on non-porous substrates, namely polypropylene, acrylic, aluminium, PVC composite material, glass, and crystalline silicon. The application of DD was performed according to methods reported in literature, where 10 µL of the dye solution (20-fold dilution of DD in 75% EtOH) was applied onto a variety of non-porous substrates via a micropipette and then subsequently visualised using a portable fluorescence microscope.

Identifying background microbiomes in an evidence recovery laboratory: A preliminary study.

16S rRNA profiling of bacterial communities may have forensic utility in the identification or association of individuals involved with criminal activities. Microbial profiling of evidence may, in the future, be performed within environments currently utilised for human DNA recovery, such as a forensic biology laboratory. It would be important to establish the background microbiome of such an environment to determine the potential presence of human or environmental microbial signatures to assist forensic scientists in the appropriate interpretation of target microbial communities.

Investigation into the presence and transfer of microbiomes within a forensic laboratory setting.

Microbial profiling within forensic science is an emerging field that may have applications in the identification of individuals using microbial signatures. It is important to determine if microbial transfer may occur within a forensic laboratory setting using current standard operating procedures (SOPs) for nuclear DNA recovery, to assess the suitability of such procedures for microbial profiling and establish the potential limitations of microbial profiling for forensic purposes. This preliminary study investigated the presence and potential transfer of human-associated microbiomes within a forensic laboratory.

Prevalence of DNA of regular occupants in vehicles.

People will deposit, redistribute and remove biological traces when they interact with their environment. Understanding the dynamics of trace DNA is crucial to assess both the optimal sampling strategy to recover traces and the relevance of DNA evidence in the context of a case. This paper addresses the prevalence of DNA of drivers, passengers, and unknown individuals in vehicles.

DNA recovery from unfired and fired cartridge cases: A comparison of swabbing, tape lifting, vacuum filtration, and direct PCR.

The ability to recover trace DNA from fired cartridge cases can help establish important leads regarding the handler of the ammunition. Over recent years, several DNA recovery techniques for fired ammunition have been published. Three techniques of significant interest include tape lifting, direct PCR, and vacuum filtration.

Challenges in Human Skin Microbial Profiling for Forensic Science: A Review.

The human microbiome is comprised of the microbes that live on and within an individual, as well as immediately surrounding them. Microbial profiling may have forensic utility in the identification or association of individuals with criminal activities, using microbial signatures derived from a personal microbiome. This review highlights some important aspects of recent studies, many of which have revealed issues involving the effect of contamination of microbial samples from both technical and environmental sources and their impacts on microbiome research and the potential forensic applications of microbial profiling.

Prevalence of DNA from the driver, passengers and others within a car of an exclusive driver.

Cars are often sampled for DNA to help identify occupants and their possible location(s) within the car. While DNA from the frequent driver is likely to accumulate over time, DNA from previous and/or subsequent occupants, and those whose DNA has inadvertently been transferred to the car, may also contribute to any samples collected. This study investigates how much DNA resides on various sites within cars, and who might contribute to these samples.

Investigation of direct and indirect transfer of microbiomes between individuals.

The human microbiome encompasses the fungi, bacteria and viruses that live on, within, and immediately surrounding the body. Microbiomes have potential utility in forensic science as an evidentiary tool to link or exclude persons of interest associated with criminal activities. Research has shown the microbiome is individualised, and that personal microbial signatures can be recovered from surfaces such as phones, shoes and fabrics.

The synthesis and characterisation of MDMA derived from a catalytic oxidation of material isolated from black pepper reveals potential route specific impurities.

This work examines the chemical synthesis of 3,4-methylenedioxy-N-methylamphetamine (MDMA) from piperonal prepared via a catalytic ruthenium tetroxide oxidation of piperine extracted from black pepper. A variety of oxidation conditions were experimented with including different solvent systems and co-oxidants. A sample of prepared piperonal was successfully converted into MDMA via 3,4-methylenedioxyphenyl-2-nitropropene (MDP2NP) and 3,4-methylenedioxyphenyl-2-propanone (MDP2P) and the impurities within each product characterised by GC-MS to give a contaminant profile of the synthetic pathway.

A study into the distribution of gunshot residue particles in the random population.

When considering the impact and value of gunshot residues (GSR) as forensic trace evidence, the likelihood of a suspect producing a positive GSR analysis result without having direct exposure to a firearm is a major consideration. Therefore, the random prevalence of GSR and 'GSR-like' residues in the wider population is a highly pertinent question when considering the probative value of such evidence. The random prevalence of GSR in two Australian jurisdictions - Victoria and South Australia - was assessed through the collection and analysis of GSR samples obtained from randomly selected members of the public.

Effect of fabric mounting method and backing material on bloodstain patterns of drip stains on textiles.

Textiles may provide valuable bloodstain evidence to help piece together events or activities at violent crime scenes. However, in spite of over 75 years of research, there are still difficulties encountered in many cases in the interpretation and identification of bloodstains on textiles. In this study, we dripped porcine blood onto three types of fabric (plain woven, single jersey knit, and denim) that are supported in four different ways (hard, taut, loose, and semi-hard, i.

Preliminary investigation of differential tapelifting for sampling forensically relevant layered deposits.

The analysis of DNA mixtures can be problematic, especially when in trace quantities such as when a biological sample is deposited onto a substrate which contains background DNA (for example, in the case of touch DNA deposited onto a garment containing the wearer's DNA). We conducted a preliminary investigation into the possibility of removing such multi-donor deposits layer by layer using a differential tape-lifting method. Two types of tape were tested using two different numbers of applications for sampling layered deposits of touch DNA/touch DNA and touch DNA/saliva, both on the same polyester-cotton plain woven material.

The complexities of DNA transfer during a social setting.

When questions relating to how a touch DNA sample from a specific individual got to where it was sampled from, one has limited data available to provide an assessment on the likelihood of specific transfer events within a proposed scenario. This data is mainly related to the impact of some key variables affecting transfer that are derived from structured experiments. Here we consider the effects of unstructured social interactions on the transfer of touch DNA.

FACS separation of non-compromised forensically relevant biological mixtures.

Although focusing attention on the statistical analysis of complex mixture profiles is important, the forensic science community will also benefit from directing research to improving the reduction of the incidence of mixtures before DNA extraction. This preliminary study analysed the use of fluorescence assisted cell sorting (FACS) for separation of cellular mixtures before DNA extraction, specifically mixtures of relatively fresh blood and saliva from two donors, prepared in 14 different mixture ratios. Improvements in the number of detectable alleles from the targeted cell type and overall profile quality were seen when compared to the results from unseparated samples.

Evaluation of tapelifting as a collection method for touch DNA.

The use of tapelifting for collection of touch DNA from fabrics is routine in many jurisdictions. However, there is a paucity of data relating to the effectiveness of different types of tapes for tapelifting, the amount of tapelifting required to generate a useful profile, and whether or not tapelifting is more effective than swabbing from various substrates. This research investigates these questions by comparing two tapes of different adhesive strength currently used in forensic casework (Scotch Magic tape and Scenesafe FAST minitapes), for sampling from touch deposits on four different fabrics-cotton flannelette, cotton drill woven fabric, polyester/cotton plain woven fabric and polyester strapping.

The human DNA content in artifacts deposited by the blowfly Lucilia cuprina fed human blood, semen and saliva.

Adult flies of some species are known to be attracted to crime scenes where they feed on the proteinaceous decomposition products of dead bodies. The flies leave deposits through excretion and regurgitation, and these artifacts often appear morphologically similar to bloodstains. To date, little consideration has been given to the possibility of the fly artifacts containing forensically useful levels of human DNA, or of flies as vectors of human DNA.

The influence of substrate on DNA transfer and extraction efficiency.

The circumstances surrounding deposition of DNA profiles are increasingly becoming an issue in court proceedings, especially whether or not the deposit was made by primary transfer. In order to improve the currently problematic evaluation of transfer scenarios in court proceedings, we examined the influence a variety of nine substrate types (six varieties of fabric, plywood, tarpaulin, and plastic sheets) has on DNA transfer involving blood. DNA transfer percentages were significantly higher (p=0.

Identification of 1-methylaminoanthraquinone on Australian polymeric bank notes.

This paper describes the examination and analysis of 1-methylaminoanthraquinone dye staining on Australian polymeric bank notes.

Quantifiler observations of relevance to forensic casework.

The Quantifiler (QF) kit is regularly used by forensic scientists for DNA quantitation. We performed in-house validation studies which revealed some interesting observations. The QF standard displayed a two-fold difference between two different lot numbers which suggests that every standard should be tested prior to use.

Increasing amplification success of forensic DNA samples using multiple displacement amplification.

Multiple displacement amplification (MDA) is capable of amplifying nanogram template amounts of DNA with high accuracy to generate micrograms of representative product. Although MDA is able to amplify small template amounts (<100 pg), increased levels of preferential amplification and allelic dropout are observed. The use of molecular crowders (polyethylene glycol 400) can decrease the amplification bias and increase amplification success.