Consideration of the probative value of single donor 15-plex STR profiles in UK populations and its presentation in UK courts

The adoption of new 15 locus STR multiplex systems into UK forensic science would be facilitated by agreed guidelines for reporting the strength of DNA evidence using likelihood ratios. To facilitate such an agreement, we present an analysis of previously published UK allele frequencies for white Caucasian, Afro-Caribbean and Indo-Pakistani populations and investigate their effect on likelihood ratios for single donor profiles. We consider the implication of the five additional loci and suggest a procedure for reporting likelihood ratios for 15-plex STR profiles.     

Interpretation of repeat measurement DNA evidence allowing for multiple contributors and population substructure

Due to the circumstances in some forensic cases, very small amounts of DNA (<100 pg) may be obtained. This, in turn, may affect the reliability of the PCR process, and so it may be advisable to repeat the amplification process for confirmatory purposes. Gill et al. [Forensic Sci. Int. 112 (2000) 17] proposed a method for the statistical evaluation of the PCR replicate information. In this paper we formalize the method proposed by Gill et al. [Forensic Sci. Int. 112 (2000) 17], and extend it to allow for cases involving mixed stains and for population substructure.     

The “Thin Dividing Line”: Prime Ministers and the Problem of Australian Nationalism, 1972–1996

This paper is concerned with the way in which Australian prime ministers gave expression to an idea of “national community” in the post–1972 era. With the declining relevance of the British connection, the departure of “great and powerful” friends from the region, the imperative of engagement with Asia and the emerging concept of Australia as a “multicultural” society, one of the central challenges for these leaders has been whether or not they could offer an alternative myth of community which would preserve social cohesion in the new times. This raises an important historical question concerning Australian political culture at this time — what happened to the need for nationalism? By examining the speeches of Prime Ministers Whitlam, Fraser, Hawke and Keating, it can be seen that far from asserting an old–style, exclusive Australian nationalism, in most cases these leaders expressed great caution and hesitation towards the idea of nationalism itself.     

The Stability of Collected Human Scent Under Various Environmental Conditions*,†

Abstract: Human scent evidence collected from objects at a crime scene is used for scent discrimination with specially trained canines. Storage of the scent evidence is usually required yet no optimized storage protocol has been determined. Storage containers including glass, polyethylene, and aluminized pouches were evaluated to determine the optimal medium for storing human scent evidence of which glass was determined to be the optimal storage matrix. Hand odor samples were collected on three different sorbent materials, sealed in glass vials and subjected to different storage environments including room temperature, ?80°C conditions, dark storage, and UVA/UVB light exposure over a 7‐week period. Volatile organic compounds (VOCs) in the headspace of the samples were extracted and identified using solid‐phase micro‐extraction–gas chromatography/mass spectrometry (SPME–GC/MS). Three‐dimensional covariance mapping showed that glass containers subjected to minimal UVA/UVB light exposure provide the most stable environment for stored human scent samples.     

Inclusion Probabilities and Dropout

Abstract: Recent discussions on a forensic discussion group highlighted the prevalence of a practice in the application of inclusion probabilities when dropout is possible that is of significant concern. In such cases, there appears to be an unpublished practice of calculation of an inclusion probability only for those loci at which the profile of interest (hereafter the suspect) is fully included among the alleles present in the crime scene sample and to omit those loci at which the suspect has alleles that are not fully represented among the alleles in the mixture. The danger is that this approach may produce apparently strong evidence against a surprisingly large fraction of noncontributors. In this paper, the risk associated with the approach of ignoring loci with discordant alleles is assessed by simulation.     

Stable isotope profiling of burnt wooden safety matches

Arson is a significant problem around the world, and is a crime which results in a low number of convictions. The scene of an arson can be varied, commercial, residential or national park, and recently cases have been identified which were initiated by a lit match. Matches can be recovered from a scene, usually in a burnt condition. The benefit of analysing unburnt matches has been researched previously [1,2]. In most cases, burnt matches are recovered from scenes, and therefore the research was extended to investigate the potential of using IRMS to analyse burnt matches. This includes samples which have been exposed to petrol, and various fire extinguishing chemicals.Matches were sectioned to reveal central unburnt portions of wood and analysed by isotope ratio mass spectrometry (IRMS). The stable isotope profile (SIP) of the wooden matchstick samples was unaffected by the presence of both petrol and a variety of fire extinguisher chemicals. Any changes seen could be attributed to the natural variability of isotopic composition encountered in a natural material such as wood. These findings were confirmed by the isotope analysis of 19 matchstick samples placed in mock fire training scenarios. The data was examined using a paired t-test and Hotellings T² test for a single sample.     

Empirical testing of estimated DNA frequencies

Direct empirical testing of forensic DNA micro-probabilities has proved difficult. Substantial support for the population genetic models on which these micro-probabilities are based has come from powerful but indirect means. However for many people empirical testing rather than models remains the ideal.Following the example set by Weir and Evett we report here a large-scale empirical test of a population genetic model incorporating substructure and relatedness. Given that all models represent simplifications of reality the fit of observed and prediction is remarkable and gives substantial support to the reliability of current methods.     

The probability of achieving full allelic representation for LCN-STR profiling of haploid cells

Modern forensic techniques allow DNA to be extracted from ever decreasing amounts of cellular material. Low copy number (LCN) profiling enables the production of STR profiles from small numbers of cells. Moreover, methods such as laser micro-dissection enables forensic scientists to potentially isolate individual cells for PCR. The DNA derived from haploid cells (semen) is a common source of forensic evidence in sexual assault cases. Haploid cells contain only half the DNA complement of diploid cells (3 pg compared to 6 pg). The smaller the number of cells sampled, the smaller the probability that there is a full representation of the alleles comprising the donor profile. This paper investigates the relationship between the number of cells sampled and the probability of full representation of all alleles in the donor sample. It also considers the effect of typing several loci as opposed to just a single locus.