Evidentiary Samples Research Articles

Usage of Expressions in Slogans from Political Campaigns: a Case Study of Bulgarian Local Elections in 2023

Campaign posters and printer billboards are reviewed in this article with a focus on the slogan. The main argument is that the analysis and the function of an ad slogan can be applied to political campaign slogans. Certain similarities can be found in the purpose of the two, but also similar techniques are used to engage the audience: by using salient expressions or conversational implicatures voters are engaged in a language game that increases the chances of the slogan fulfilling its purpose. For this reason, the theory of implicatures and the Graded salience hypothesis are briefly reviewed. The message becomes easier to grasp and remember because it uses familiar expressions as it is shown in the evidentiary sample.

Emerging Developments in DNA Technology and Their Potential Implications for the Criminal Justice System of Pakistan

DNA-based evidence has collected substantial trust in the Criminal Court system. DNA evidence possesses the utmost probative value among all reasonable and accurate claims in the realm of personal identity. An example of a standard step in a DNA investigation is comparing evidentiary samples, such as semen in the case of rape, with a known or reference sample, such as blood from the suspect. Utilizing forensic tools such as DNA profiling could significantly enhance the fairness of the justice system by ensuring equitable treatment for all individuals in court. Both scientific and legal communities have reached a consensus on the truth of this matter, as evidenced by their extensive literature that delves into its theoretical and practical dimensions. Frequently, courts have concurred with the DNA evidence. In recent years, Scientific and Expert Testimony has gained increased utility in complex and specialized domains. Undoubtedly, the assistance of a professional is vital when it comes to resolving a criminal case.

A robust interpolation-based method for forensic soil provenancing: A Bayesian likelihood ratio approach

Soil is a complex and spatially variable material that has a demonstrated potential as a useful evidence class in forensic casework and intelligence operations. Here, the capability to spatially constrain police search areas and prioritise resources by triaging areas as low and high interest is advantageous. Conducted between 2017 and 2021, a forensically relevant topsoil survey (0–5 cm depth; 1 sample per 1 km2) was carried out over Canberra, Australia, aiming to document the distribution of chemical elements in an urban/suburban environment, and of acting as a testbed for investigating various aspects of forensic soil provenancing. Geochemical data from X-Ray Fluorescence (XRF; for total major oxides) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS; for trace elements) following a total digestion (HF + HNO3) of the fused XRF beads were obtained from the survey’s 685 topsoil samples (plus 138 additional quality control samples and six “Blind” simulated evidentiary samples). Using those “Blind” samples, we document a likelihood ratio approach where for each grid cell the analytical similarity between the grid cell and evidentiary sample is attributed from a measure of overlap between the two Cauchy distributions, including appropriate uncertainties. Unlike existing methods that base inclusion/exclusion on an arbitrary threshold (e.g., ± three standard deviations), our approach is free from strict binary or Boolean thresholds, providing an unconstrained gradual transition dictated by the analytical similarity. Using this provenancing model, we present and evaluate a new method for upscaling from a fine (25 m x 25 m) interpolated grid to a more appropriate coarser (500 m x 500 m) grid. In addition, an objective method using Random Match Probabilities for ranking individual variables to be used for provenancing prior to receiving evidentiary material was demonstrated. Our results show this collective procedure generates more consistent and robust provenance maps when applied to two different interpolation algorithms (e.g., inverse distance weighting, and natural neighbour), with different grid placements (e.g., grid shifts to the north or east) and by different theoretical users (e.g., different computer systems, or forensic geoscientists).

A quantifiler™ trio-based HRM screening assay for the accurate prediction of single source versus mixed biological samples.

At present, the forensic DNA workflow is not capable of providing information about the contributor status (single source vs. multiple contributors) of evidentiary samples prior to end-point analysis. This exacerbates the challenges inherent to mixtures and low-template DNA samples. If additional sample information could be provided earlier in the workflow, protocols could be implemented to mitigate these challenges. An integrated Quantiplex®- high resolution melt (HRM) assay was shown to be effective in distinguishing between single source and mixture DNA samples; however, integration of the HRM assay into a more commonly used chemistry would be beneficial to the practitioner community. Thus, the assay was redesigned as an integrated Quantifiler™ Trio-HRM assay, which included the identification of a new DNA-binding dye, an increased reaction volume, and the establishment of new data analysis and standard curve metrics for all targets. This redesigned assay produced quantification values and qualitative values that were comparable to those produced when the same samples were tested using the standard Quantifiler™ Trio chemistry and settings. Further, STR profiles generated with quantification values produced from the integrated Quantifiler™ Trio-HRM assay and standard Quantifiler™ Trio chemistry were complete and fully concordant. Most importantly, the integrated Quantifiler™ Trio-HRM assay was able to accurately predict whether a sample was single source or a mixture 79.2% of the time, demonstrating the potential of this approach. With the incorporation of an expanded training set for prediction modeling, and completion of critical developmental validation studies, this assay could prove useful to the forensic DNA practitioner community.

Evaluation and Verification of a microRNA Panel Using Quadratic Discriminant Analysis for the Classification of Human Body Fluids in DNA Extracts.

There is significant interest in the use of miRNA analysis for forensic body fluid identification. Demonstrated co-extraction and detection in DNA extracts could make the use of miRNAs a more streamlined molecular body fluid identification method than other RNA-based methods. We previously reported a reverse transcription-quantitative PCR (RT-qPCR) panel of eight miRNAs that classified venous and menstrual blood, feces, urine, saliva, semen, and vaginal secretions using a quadratic discriminant analysis (QDA) model with 93% accuracy in RNA extracts. Herein, miRNA expression in DNA extracts from 50 donors of each body fluid were tested using the model. Initially, a classification rate of 87% was obtained, which increased to 92% when three additional miRNAs were added. Body fluid identification was found to be reliable across population samples of mixed ages, ethnicities, and sex, with 72-98% of the unknown samples classifying correctly. The model was then tested against compromised samples and over biological cycles, where classification accuracy varied, depending on the body fluid. In conclusion, we demonstrated the ability to classify body fluids using miRNA expression from DNA extracts, eliminating the need for RNA extraction, greatly reducing evidentiary sample consumption and processing time in forensic laboratories, but acknowledge that compromised semen and saliva samples can fail to classify properly, and mixed sample classification remains untested and may have limitations.

The Lundy murders: the role and reliability of forensic neuropathology practice

Mark Lundy was convicted of killing his wife and daughter in 2002 and again in 2015 after a retrial ordered by the Privy Council. His conviction continues to divide public opinion in New Zealand. A key piece of evidence was the presence of small smears on a shirt which prosecution experts identified as central nervous system tissue relying on immunohistochemistry. The successful challenge to his original conviction was part motivated by arguments challenging the reliability of the latter in forensic practice. This has again come under scrutiny following a 2016 report by the US President’s Council of Advisors on Science and Technology. The PCAST concluded that there were two important deficiencies in ensuring scientific validity of so-called ‘feature-comparison methods’. These are procedures by which an examiner seeks to determine whether an evidentiary sample is or is not associated with a source sample based on similar features. Proponents of Lundy’s innocence argue that the application of immunohistochemistry must be regarded as a subjective feature-comparison method. There was a need for (1) clarity about the scientific standards for the validity and reliability of forensic methods and (2) the need to evaluate specific forensic methods to determine whether they have been scientifically established to be valid and reliable. The report emphasised 2 key elements that are required to meet the scientific criteria of foundation validity: (1) a reproducible and consistent procedure and (2) empirical measurements from multiple independent studies of a method’s false positive rate and sensitivity. It is this author’s position that the manner in which the immunohistochemistry was applied in the Lundy case to identify central nervous system tissue was sufficiently robust in terms of rigor and reproducibility and that to insist otherwise would be tantamount to believing in biological alchemy.

A method to enable forensic genetic genealogy investigations from DNA mixtures

The presence of more than one DNA contributor in an evidentiary sample may preclude attempts to use forensic genetic genealogy to develop an investigative lead. To address this issue, we developed a workflow for deconvolution of SNP mixtures into single source profiles that are suitable for matching against a genealogical database. Using the method, two-contributor DNA mixtures assayed using a commercial SNP typing kit can produce informative match results for both major and minor contributors.

Review of direct PCR and Rapid DNA approaches to streamline sexual assault kit testing.

Crime laboratories have been faced with large casework backlogs due to lengthy processing times, limited resources and scientists, and rising crime rates. Evidence related to sexual assault crimes, specifically sexual assault kits (SAKs), heavily contribute to the reported backlogs. Although more sensitive, faster chemistries and automated techniques have been implemented over the years, the traditional STR workflow remains relatively unchanged. Enhanced workflows such as direct PCR and Rapid DNA have the potential to streamline the processing of forensic evidence items including those commonly submitted in SAKs, but the FBI QAS guidelines restrict CODIS-approved labs from implementing these methods for forensic samples. Recent studies have shown decreased turnaround times and improved or comparable profiling success with both approaches. However, review of the literature shows a lack of in-depth research comparing traditional DNA workflows to faster and more sensitive direct PCR and/or Rapid DNA approaches for evidentiary samples, especially for SAKs. By providing the forensic science and criminal justice communities with the strengths and limitations of direct PCR and Rapid DNA methods, stakeholders and policy makers may be better informed.

Design and optimization of a 16S microbial qPCR multiplex for the presumptive identification of feces, saliva, vaginal and menstrual secretions.

Molecular methods for body fluid identification have been extensively researched in the forensic community over the last decade, mostly focusing on RNA‐based methods. Microbial DNA analysis has long been used for forensic applications, such as postmortem interval estimations, but only recently has it been applied to body fluid identification. High‐throughput sequencing of the 16S ribosomal RNA gene by previous research groups revealed that microbial signatures and abundances vary across human body fluids at the genus and/or species taxonomic level. Since quantitative PCR is still the current technique used in forensic DNA analysis, the purpose of this study was to design a qPCR multiplex targeting the 16S gene of Bacteroides uniformis, Streptococcus salivarius, and Lactobacillus crispatus that can distinguish between feces, saliva, and vaginal/menstrual secretions, respectively. Primers and probes were designed at the species level because these bacteria are highly abundant within their respective fluid. The validated 16S triplex was evaluated in DNA extracts from thirty donors of each body fluid. A classification regression tree model resulted in 96.5% classification accuracy of the population data, which demonstrates the ability of this 16S triplex to presumptively identify these fluids with high confidence at the quantification step of the forensic workflow using minimal input volume of DNA extracted from evidentiary samples.

Forensic soil provenancing in an urban/suburban setting: A simultaneous multivariate approach.

Soil is a ubiquitous material at the Earth's surface with potential to be a useful evidence class in forensic and intelligence applications. Compositional data from a soil survey over North Canberra, Australian Capital Territory, are used to develop and test an empirical soil provenancing method. Mineralogical data from Fourier Transform InfraRed spectroscopy (FTIR) and geochemical data from X‐Ray Fluorescence (XRF; for total major oxides) and Inductively Coupled Plasma‐Mass Spectrometry (ICP‐MS; for both total and aqua regia‐soluble trace elements) are obtained from the survey's 268 topsoil samples (0–5 cm depth; 1 sample per km2). The simultaneous provenancing approach is underpinned by (i) the calculation of Spearman's correlation coefficients (rS ) between an evidentiary sample and all the samples in the database for all variables generated by each analytical method; and (ii) the preparation of an interpolated raster grid of rS for each evidentiary sample and method resulting in a series of provenance rasters (“heat maps”). The simultaneous provenancing method is tested on the North Canberra soil survey with three “blind” samples representing simulated evidentiary samples. Performance metrics of precision and accuracy indicate that the FTIR (mineralogy) and XRF (geochemistry) analytical methods offer the most precise and accurate provenance predictions. Maximizing the number of analytes/analytical techniques is advantageous in soil provenancing. Despite acknowledged limitations, it is concluded that the empirical soil provenancing approach can play an important role in forensic and intelligence applications.

Forensic soil provenancing in an urban/suburban setting: A sequential multivariate approach.

Compositional data from a soil survey over North Canberra, Australian Capital Territory, are used to develop and test an empirical soil provenancing method. Mineralogical data from Fourier transform infrared spectroscopy (FTIR) and magnetic susceptibility (MS), and geochemical data from X‐ray fluorescence (XRF; for total major oxides) and inductively coupled plasma‐mass spectrometry (ICP‐MS; for both total and aqua regia‐soluble trace elements) are performed on the survey's 268 topsoil samples (0–5 cm depth; 1 sample per km2). Principal components (PCs) are calculated after imputation of censored data and centered log‐ratio transformation. The sequential provenancing approach is underpinned by (i) the preparation of interpolated raster grids of the soil properties (including PCs); (ii) the explicit quantification and propagation of uncertainty; (iii) the intersection of the soil property rasters with the values of the evidentiary sample (± uncertainty); and (iv) the computation of cumulative provenance rasters (“heat maps”) for the various analytical techniques. The sequential provenancing method is tested on the North Canberra soil survey with three “blind” samples representing simulated evidentiary samples. Performance metrics of precision and accuracy indicate that the FTIR and MS (mineralogy), as well as XRF and total ICP‐MS (geochemistry) analytical methods, offer the most precise and accurate provenance predictions. Inclusion of PCs in provenancing adds marginally to the performance. Maximizing the number of analytes/analytical techniques is advantageous in soil provenancing. Despite acknowledged limitations and gaps, it is concluded that the empirical soil provenancing approach can play an important role in forensic and intelligence applications.

Damage patterns observed in mtDNA control region MPS data for a range of template concentrations and when using different amplification approaches.

Massively parallel sequencing (MPS) of mitochondrial (mt) DNA allows practitioners the ability to fully resolve heteroplasmic sites. In forensic DNA analysis, identifying heteroplasmy (a naturally occurring mixture of two mtDNA profiles) can provide additional mtDNA profile information which can lead to an increase in the discrimination potential of an mtDNA match between an evidentiary sample and reference source. Forensic samples such as hair and skeletal remains, especially older, more compromised samples, can often exhibit DNA damage. Because both damage and heteroplasmy can manifest as a mixture of two nucleotides, it is important to differentiate between the two conditions when interpreting mtDNA MPS data. In this study, DNA damage was applied under controlled conditions to samples containing a range of template concentrations, including some with identified heteroplasmy. Damage was applied via storage in water at room temperature on samples diluted before or after storage to mimic low template scenarios. Damage was assessed with respect to the following areas: mtDNA quantification and degradation ratios, MPS read depth, MPS profile results, overall damage rates, and the interpretation of heteroplasmy. Datasets were generated to assess and compare two different amplification and library preparation strategies: the Promega PowerSeq™ CRM Nested System kit and a 1.16kb target amplicon of the entire mtDNA control region followed by a Nextera® XT library preparation. The results of this study provide an evaluation of the Promega 10-plex MPS procedure as an improved process to mitigate the impact of mtDNA damage on low template samples. Some of the negative effects of damage observed in this study were a decrease in mtDNA yield by 20-30% and lower quality MPS sequencing results. These effects were observed more frequently when samples were diluted prior to inducing damage, illustrating that low template samples are more susceptible to damage. The findings of this study will assist forensic laboratories in differentiating between damage and heteroplasmy, which is essential when developing robust mtDNA MPS interpretation guidelines such as setting appropriate reporting thresholds.

Forensic Source Conclusions

Abstract. Forensic science evidence may be the most powerful weapon in the arsenal of law enforcement officials and prosecutors. As such, it is important to be aware of factors that threaten the validity of forensic source conclusions (e.g., “This bullet was fired from that gun”). This paper identifies 20 threats to the validity of forensic source conclusions including threats that spring from (a) the evidentiary samples themselves, (b) forensic examiners and the procedures they use, (c) features of the law, and (d) cognitive limitations of jurors and others who must weigh forensic science source claims.

Forensic Source Conclusions: Twenty Threats to Validity

Forensic science evidence may be the most powerful weapon in the arsenal of law enforcement officials and prosecutors. As such, it is important to be aware of factors that threaten the validity of forensic source conclusions (e.g., “This bullet was fired from that gun”). This paper identifies 20 threats to the validity of forensic source conclusions including threats that spring from: (a) the evidentiary samples themselves, (b) forensic examiners and the procedures they use, (c) features of the law, and (d) cognitive limitations of jurors and others who must weigh forensic science source claims.

DNA backlog reduction strategy: Law enforcement agency partnerships for a successful biological screening laboratory

In 2009, the Palm Beach County Sheriff’s Office Forensic Biology Unit developed an innovative DNA backlog strategy to construct and operate a centralized biological processing laboratory (BPL) within a law enforcement agency, the Boca Raton Police Services Department. The BPL became fully operational in 2012 and obtained accreditation in 2017. This coordinated, multi-agency agreement resulted in a streamlined process exemplifying several benefits such as communicating timely testing results, decreasing the case turnaround time, and decreasing the DNA case backlog. This paper provides a summary of the necessary considerations of location, construction, personnel, and services when constructing a BPL, as well as, provides a comparison of initial completion dates and ultimate completion dates over a three-year period from 2016 to 2018. Three LEAs submitted 613 cases to the BPL commensurate with jurisdictional population. Performance metrics such as types and number of criminal cases screened; the number of samples forwarded for PBSO DNA testing; the turnaround time to handle, screen, or analyze a forensic sample; evidentiary samples; and the number of profiles entered into the Combined DNA Index System (CODIS) database are reported. For example, prior to this DNA backlog reduction strategy, the FBU was taking an average of 153 days to handle, screen, or analyze a forensic sample from submission to final report and there was a backlog of 679 cases. From 2016 to 2018, the total average turnaround time for BPL decreased from 30.5 to 19.6 days, (35.8% decrease); and the FBU Request turnaround time decreased from 153 to 80 days (35% decrease). Monitoring laboratory metrics demonstrate the efficacy of the DNA backlog reduction strategy.There are several takeaway lessons from this experience, including (1) engaging legal counsel early to outline necessary legal procedures and the timeline; (2) bringing all stakeholders “to the table” early to discuss expectations, as well as legal and operational responsibilities; and (3) creating a realistic timeline as well as establishing a comprehensive memorandum of understanding by which all parties understand their roles and responsibilities. Understanding laboratory and non-laboratory policy issues is critical to implementation success and the efficacy of a BPL as a DNA backlog reduction strategy.

Prevalence and impact of PCR artifacts from soil samples using the Applied Biosystems™ GlobalFiler™ PCR amplification kit: Interference of non-human artifacts in DNA profiles from a homicide investigation

Non-human artifacts have been observed in a range of forensic typing methods. This is primarily due to the condition and potential environmental contamination of many evidentiary samples. Here, a case example of non-human artifact peaks is presented to illustrate ways in which to recognize potential artifact peaks as well as mitigate their effect on interpretation.

Demonstration of a mitochondrial DNA-compatible workflow for genetically variant peptide identification from human hair samples

Hair is an evidentiary sample that typically does not provide sufficient nuclear DNA for forensic analysis. Therefore, state-of-the-art forensic examination for hair samples include subjective microscopic evaluation, mitochondrial DNA (mtDNA) analysis, and more recently, proteomic genotyping that uses protein variation in the form of genetically variant peptides (GVPs) to infer single nucleotide polymorphism (SNP) alleles. Since many cases involve limited sample amounts (approximately 2 cm or less), any additional destructive testing (besides mtDNA) would be excluded. If a mtDNA-compatible protein extraction workflow could be developed, GVPs would provide additional forensic value without sacrificing any portion of the original hair sample. Here, we demonstrate an optimized method that can be used to obtain both whole genome mtDNA and putative GVP profiles from a single limited hair sample. The method involves urea-based extraction of proteins from hair, followed by buffer exchange and protease digestion. Peptides are eluted through a 30 kDa membrane and analyzed using traditional proteomic techniques. DNA is subsequently extracted from the filter and analyzed using whole mt-genome analysis. The method was verified with a range of hair sample types (head, pubic, and arm hair) from a diverse cohort of 22 individuals. Specifically, putative GVP profiles and mtDNA haplotypes concordant with buccal swab samples from the same donor were obtained from 22 individuals. Further, the utility of the method was verified across two different laboratories. The method is applicable for proteomic-based GVP analysis and mt-genome analysis for forensic research applications.

Effiziente DNA-Extraktion aus geringen Probenmengen

As the number of evidentiary samples submitted to clinical or forensic laboratories increases, so does the demand for automated system solutions which enable higher throughput and reliable results. Nucleic acid purification for downstream analysis must meet high requirements, since purity and yield determine the quality of final results. Promega’s Maxwell® Rapid Sample Concentrator 48 (RSC 48) provides a reliable purification method using an automated workflow for extraction of nucleic acid from a variety of sample types.

The study of ABO genotyping for forensic application

ABO blood typing has been used for personal identification and paternity testing in forensic medicine and criminal investigations for many years, since the ABO blood types obtained from evidentiary samples are usually one of the initial pieces of information available that could lead to identification of the suspect. Because of this importance of the initial information, many different molecular typing methods have been reported to complement routine serological ABO blood typing in forensics. The method using a multiplex allele-specific primer set enables the detection of six SNP sites in the ABO gene (nt 261, 526 and 803) along with the determination of ABO genotypes from their combinations, which is applied to forensic science casework samples in this paper. An internal validation study has been conducted to show that this method successfully determined ABO genotypes of blood, blood stain, saliva stain, buccal swab, vaginal fluid, hair and low copy number sample with high sensitivity, accuracy, and reproducibility. These results suggest that the method using a multiplex allele-specific primer set is so reliable that it can be used as a rapid screen for forensic science casework samples before multi locus short tandem repeat (STR) profiling is performed.

Direct and comprehensive analysis of dyes based on integrated molecular and structural information via laser desorption laser postionization mass spectrometry

Laser desorption laser postionization time-of-flight mass spectrometry (LDPI-TOFMS) was employed for direct analysis and determination of typical basic dyes. It was also used for the analysis and comprehensive understanding of complex materials such as blue ballpoint pen inks. Simultaneous emergences of fragmental and molecular information largely simplify and facilitate unambiguous identification of dyes via variable energy of 266nm postionization laser. More specifically, by optimizing postionization laser energy with the same energy of desorption laser, the structurally significant results show definite differences in the fragmentation patterns, which offer opportunities for discrimination of isomeric species with identical molecular weight. Moreover, relatively high spectra resolution can be acquired without the expense of sensitivity. In contrast to laser desorption/ionization mass spectrometry (LDI-MS), LDPI-MS simultaneously offers valuable molecular information about dyes in traces, solvents and additives about inks, thereby offering direct determination and comprehensive understanding of blue ballpoint inks and giving a high level of confidence to discriminate the complicated evidentiary samples. In addition, direct analysis of the inks not only allows the avoidance of the tedious sample preparation processes, significantly shortening the overall analysis time and improving throughput, but allows minimized sample consumption which is important for rare and precious samples.