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1.
Forensic Sci Int ; 327: 110988, 2021 Oct.
Article in English | MEDLINE | ID: mdl-34521020

ABSTRACT

The development of fingermarks on reflective surfaces is often a challenge regarding the photography of images with overlapping lines, low contrast and reflections, especially considering that many forensic laboratories are supplied only with basic instrumentation for fingerprint analysis. The present study overviews these difficulties and proposes a combination of chemical and optical procedures, using low-cost products and equipment, to develop fingermarks on silver mirror surfaces. The chemical treatment promotes the delimitation of the substrate, transforming the reflective surface into a transparent surface. The results were statistically analyzed, indicating quality improvement of natural fingermarks pictures taken with standard digital camera on transparent surface. There was good observation of details and minutiae, even for samples recovered several days or weeks after deposition. The suggested method substantially modifies the composition of the substrate without any contact with the fingermark, preserving its characteristics and properties. Like other nondestructive methodologies, this approach could be prioritized over methods that directly change the evidence itself and allows for the photography of the fingermark in unaltered condition. Lastly, it does not impact on the efficiency of subsequent exams.


Subject(s)
Dermatoglyphics , Forensic Sciences/methods , Photography , Silver/chemistry , Female , Humans , Male , Surface Properties
2.
J Forensic Leg Med ; 83: 102253, 2021 Oct.
Article in English | MEDLINE | ID: mdl-34543893

ABSTRACT

BACKGROUND: Blast related deaths are often shrouded by diagnostic and medicolegal complexities requiring multidisciplinary expertise in order to gauge accurate identification of the victims and document scientific investigations comprehensively. In the advent of more sophisticated technology, anthropologic methods can now be applied into post mortem imaging interpretation. The traditional imaging roles of characterizing osseous fragmentation, detecting and localizing foreign bodies can be expanded to simulate and support physical anthropologic examination to assist in documentation for court proceedings. CASE PRESENTATION: An assemblage of unidentified, incomplete, highly fragmented skeletal remains were found scattered on a bare area of land in a forest. There was evidence of an explosion given the pattern of scattered evidentiary material of explosive and ballistic nature. Laboratory analysis of white powder found within the explosive material confirmed the presence of high impact C4-explosive trace containing cyclotrimethylene trinitramin [Royal Demolition Explosive (RDX)] & pentaerythritol tetranitrate (PETN). It took meticulous multidisciplinary efforts to confirm the identity of the victim that was marred by the severe fragmentation and skeletalization of the remains. The initial radiologic interpretation focused more on identification of foreign bodies and supporting documentation of fragmentation. With the current availability of post computed tomography (PMCT) in our center, we reexamined the value and potential of PMXR and PMCT as an adjunctive tool for biological profiling. CONCLUSION: This was the first case of C4-blast related death reported in Malaysia. The multidisciplinary approach in efforts to identify the victim may serve as a guide in managing, coordinating and maximizing the expertise of different forensic specialists, with emphasis on anthropologic and radiologic collaboration.


Subject(s)
Age Determination by Skeleton , Blast Injuries , Body Remains/injuries , Bone and Bones/injuries , Forensic Anthropology/methods , Forensic Sciences/methods , Sex Determination by Skeleton , Adult , Body Remains/anatomy & histology , Body Remains/diagnostic imaging , Bone and Bones/anatomy & histology , Bone and Bones/diagnostic imaging , Explosive Agents/analysis , Female , Humans , Malaysia , Radiography , Tomography, X-Ray Computed
3.
Forensic Sci Int ; 327: 110981, 2021 Oct.
Article in English | MEDLINE | ID: mdl-34482285

ABSTRACT

Multi-metal deposition (MMD) is a versatile fingermarks detection technique adapted from the colloidal gold biolabeling. However, the tedious procedures of MMD makes it receive little attention compared with other methods. The aim of this study is to evaluate the efficacy of MMD technique on several common fabrics, which is considered notoriously challenging for latent fingermark detection. Four different MMD formulations were examined to process fingermarks deposited on nylon taffeta, polyester taffeta, polyester pongee and cotton sateen to determine the most suitable one and the influence of aging and water immersion were also determined through subsequent experiments. It was found that MMD I outperformed other three formulations and obtained excellent results on nylon taffeta, polyester taffeta and satin ribbon, with polyester taffeta and satin ribbon providing more than 30% of identifiable marks even for fingermarks aged over 28 days. Cotton sateen and oxford cloth failed to produce ridge details but evidence of "touch" were successfully visualized, which may contribute to further DNA extraction. Water immersion did have some observable influence on the quality of detected marks as part of the MMD reactant within fingermarks lost during immersion, but the result from nylon taffeta and satin ribbon is still satisfying with the percentage of marks scored 3 and 4 reached 30%. The result of this study confirmed the capability of MMD I in treated with fingermarks on several kinds of fabrics, and shows potential to promote this non-instrumentation dependent technique.


Subject(s)
Dermatoglyphics , Forensic Sciences/methods , Manufactured Materials , Female , Gold Colloid/chemistry , Humans , Male , Metal Nanoparticles/chemistry , Nylons , Polyesters , Surface Properties , Textiles
4.
J Forensic Sci ; 66(6): 2208-2217, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34342895

ABSTRACT

The issue of distinguishing between the same-source and different-source hypotheses based on various types of traces is a generic problem in forensic science. This problem is often tackled with Bayesian approaches, which are able to provide a likelihood ratio that quantifies the relative strengths of evidence supporting each of the two competing hypotheses. Here, we focus on distance-based approaches, whose robustness and specifically whose capacity to deal with high-dimensional evidence are very different, and need to be evaluated and optimized. A unified framework for direct methods based on estimating the likelihoods of the distance between traces under each of the two competing hypotheses, and indirect methods using logistic regression to discriminate between same-source and different-source distance distributions, is presented. Whilst direct methods are more flexible, indirect methods are more robust and quite natural in machine learning. Moreover, indirect methods also enable the use of a vectorial distance, thus preventing the severe information loss suffered by scalar distance approaches. Direct and indirect methods are compared in terms of sensitivity, specificity, and robustness, with and without dimensionality reduction, with and without feature selection, on the example of hand odor profiles, a novel and challenging type of evidence in the field of forensics. Empirical evaluations on a large panel of 534 subjects and their 1690 odor traces show the significant superiority of the indirect methods, especially without dimensionality reduction, be it with or without feature selection.


Subject(s)
Forensic Sciences/methods , Hand , Odorants , Adolescent , Adult , Aged , Aged, 80 and over , Child , Female , Gas Chromatography-Mass Spectrometry , Humans , Likelihood Functions , Logistic Models , Male , Middle Aged , Principal Component Analysis , Young Adult
5.
J Chromatogr A ; 1654: 462462, 2021 Sep 27.
Article in English | MEDLINE | ID: mdl-34411835

ABSTRACT

The identification of ILRs in fire investigations has attracted great attention for decades, and background at fire scenes caused complex interference on ILR identification by contributing characteristic compounds. Aiming at exploring the correlation between the interference extent to gasoline identification and chemical composition/structure, two polystyrene-butadiene rubbers (SBr) with typical styrene contents involving alkylbenzene in molecules were selected particularly. The free burning residues in the presence and absence of gasoline were collected and analyzed via gas chromatography-mass spectrometry. It is striking that SBr with typical styrene content caused the most remarkable interference to gasoline identification as far as reported since it is even impossible to be distinguished from gasoline through chromatography profiles. Additionally, the molecular structure together with the chemical composition influences the interference extent as well. To trace the source of the remarkable interference from SBr, polystyrene, polybutadiene, as well as one polystyrene-butadiene-styrene block copolymer, were picked particularly due to their specific chemical relations. The results of target compounds analysis on the corresponding combustion residues revealed that the remarkable interference of SBrs originated from the combination of 'styrene' and 'butadiene' by contributing different target compounds. The results provide further support for the proposal of the correlation of the interferents chemical compositions with the interference extent. Furthermore, this study provides important references for fire debris analysis by predicting the interference of different substrates on the basis of their chemical composition.


Subject(s)
Butadienes , Fires , Forensic Sciences , Gasoline , Butadienes/chemistry , Forensic Sciences/methods , Gas Chromatography-Mass Spectrometry , Gasoline/analysis , Polystyrenes/chemistry
6.
J Forensic Sci ; 66(6): 2424-2437, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34363402

ABSTRACT

One of the first challenges that crime scene examiners have is determining if a substance is blood before performing analysis. Conventional methods of detecting blood involve the use of chemicals and different wavelengths of light in tandem with digital photography. However, these methods are destructive or provide false positives. Visible wavelength hyperspectral imaging (HSI) is a noncontact blood detection method that has been proven to provide accurate and reliable results. A novel application of this technique has been used for the detection and positive identification of bloodstained footwear marks, of different dilutions ranging from undiluted to 1:50 with distilled water, and on a range of substrates, and colors. Comparisons between HSI and conventional digital photography were made using a grading scale and analyzed using Mann-Whitney U-tests. The HSI technique was able to detect a statistically significant greater amount of tread detail on white tiles, laminate, carpet, and blue tiles compared with the digital photography technique, which was only superior on black tiles. Critically, the HSI technique was also able to determine that the footwear marks were made in blood. These results show that HSI will be useful in forensic investigations, where it is known that the perpetrator has walked through the victim's blood and left a trail of footwear marks at the crime scene. Even if the perpetrator had time to clean up afterward resulting in diluted stains, HSI would still be able to detect bloodstained footwear marks with a greater amount of detail compared with digital photography.


Subject(s)
Blood Stains , Hyperspectral Imaging , Image Processing, Computer-Assisted , Photography , Shoes , Forensic Sciences/methods , Humans
7.
Forensic Sci Int ; 325: 110894, 2021 Aug.
Article in English | MEDLINE | ID: mdl-34271326

ABSTRACT

This paper describes the involvement of our laboratory in a Western Australian 'cold-case' investigation that spanned 24 years. The investigation was widely considered to be the largest in Australian history. During the investigative phase, our laboratory was tasked with the collection of trace evidence of all types in connection with a sexual assault and two homicides that were suspected to be related. Textile fibres represented the vast majority of trace evidence recovered. A much greater quantity of fibres (>10,800) was collected than would be typical for a routine case, as fibres of any colour or type were potentially of investigative value. The investigation was unprecedented in its scale, and presented numerous challenges in terms of evidence recovery, analysis, interpretation, reporting, and provision of testimony. A textile fibre microspectrophotometric (MSP) database was developed specifically for the interpretation of data in connection with the investigation. The database currently contains over 25,000 normalised and first derivative spectra of casework, validation and reference textile fibres. A fibre comparison strategy was devised, involving the identification of preliminary fibre groups on the basis of corresponding/similar MSP spectra, and verification of these groups via brightfield and fluorescence comparison microscopy. A potential link to an automotive source was identified for one of the homicide victims during the investigative phase. After identification of a suspect, a total of 98 fibres recovered from victims and from a seized motor vehicle were found to correspond in properties to six different fibre types from known textile sources in connection with the suspect. A highly publicised criminal trial was held, and textile fibre evidence provided a major contribution to the trial findings, in which the accused was found guilty of two homicides.


Subject(s)
Databases, Factual , Forensic Sciences/methods , Textiles , Australia , Homicide , Humans , Microspectrophotometry , Spectroscopy, Fourier Transform Infrared
8.
J Forensic Sci ; 66(6): 2413-2423, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34323303

ABSTRACT

The Natural Resources Conservation Service-Kellogg Soil Survey Laboratory has a large publicly available database of laboratory analyses of soil horizons collected from soil profiles largely from the United States. Among these soil properties are mineral grain counts from selected sand and silt fractions of soil horizons, performed by polarized light microscopy (PLM). These grain counts of over 20,000 fractions from 7534 sites provide a substantial reference that a forensic soil examiner could use to substantiate the rarity or commonness of a mineral species. The statement of the rarity or commonness of various minerals provide juries with additional context for the interpreting the results of a forensic soil comparison within the framework of a trial. The grain count data at specific locations can also be assessed to aid in soil provenance investigations, for cases where there are grain-counted sites in relevant locations. Two examples of application of these to data to soil evidence are included, one relating soil the rarity of a mineral (andalusite) to provide context in a soil comparison and one to aid in narrowing target regions in a soil provenance investigation.


Subject(s)
Minerals/analysis , Soil/chemistry , Forensic Sciences/methods , Geologic Sediments/analysis , Geology/methods
9.
Forensic Sci Int ; 325: 110824, 2021 Aug.
Article in English | MEDLINE | ID: mdl-34098471

ABSTRACT

Being able to identify the author of an anonymous or disputed document is an important task in forensic science. This can be treated as a form of pattern evidence based on writing style, but the subjective analysis of writing style may have all the well-known problems of other forms of subjective pattern evidence. In this paper, we demonstrate a computer program to address these issues. This program analyzes a pair of documents (a known document and a questioned document) to determine if they were written by the same author. More importantly, this paper also validates the accuracy of this program through a large-scale series of controlled experiments involving English language blogs. Across more than 32,000 different document pairs, the system achieved a measured accuracy of 77%. This paper concludes that this system not only addresses a key problem in forensic linguistics, but also provides the repeatability, reproducibility, and measured accuracy levels that are key to the advancement of forensic science.


Subject(s)
Authorship , Forensic Sciences/methods , Linguistics , Humans , Reproducibility of Results
10.
J Forensic Sci ; 66(5): 1658-1668, 2021 Sep.
Article in English | MEDLINE | ID: mdl-34121191

ABSTRACT

In a strangulation case, when a necktie is used as a murder weapon, the dyed silk single fiber becomes an important evidence sample to solve the crime. Dyed silk single fibers contain elements, such as Cr and Co, which are obtained from dyeing using metal mordants. Currently, there are no nondestructive and sufficiently sensitive elementary analytical methods for the forensic analysis of single fibers. Therefore, in this study, eight commercially available red silk samples were collected and used for total reflection X-ray fluorescence (TXRF) and synchrotron radiation X-ray fluorescence (SR-XRF) spectrometry. Benchtop TXRF detected both S in the silk protein and Cl and Ca, which are elements absorbed from the environment by silkworms, but also Cr, which is a dyeing derivative for metal mordants. The presence of Cr and Zn, in addition to the Zn/Cr signal intensity ratios, was reported to be particularly useful identifiers. In SR-XRF, the presence of Cr, Co, Zn, and Br and the Zn/Cr signal intensity ratios were reported to be useful discriminating indicators. In this study, the nondestructive discrimination capabilities of TXRF and SR-XRF measurements for the samples were found to be 85.7% and 100%, respectively. Therefore, we propose a combination of TXRF and SR-XRF as a new nondestructive single fiber identification method for forensic science. Moreover, if partial destruction of a single fiber is allowed, the observation of the cross section and micro-Fourier-transform infrared spectroscopy measurements is useful for identifying red silk fibers.


Subject(s)
Silk , Spectrometry, X-Ray Emission/methods , Textiles , Color , Forensic Sciences/methods , Metals/analysis , Microscopy , Silk/chemistry
11.
Forensic Sci Int ; 325: 110882, 2021 Aug.
Article in English | MEDLINE | ID: mdl-34182205

ABSTRACT

Ground-penetrating radar (GPR) is an established geophysical technique used extensively for the accurate reconstruction of the shallow (<10 m) subsurface. Reconstructions have largely been completed and presented as 2D vertical and horizontal planes, leaving limited visualization of subsurface 3D shapes and their spatial relationships. With technological advancements, particularly the availability and integration of various software platforms, 3D modelling of GPR data is now emerging as the new standard. However, despite these developments, there remains an inadequate examination and testing of these techniques, particularly in determining if their application is beneficial and warranted. In this study we conducted a GPR grid survey on a churchyard cemetery to generate and evaluate 2D and 3D-modelled reconstructions of the cemetery burial sites. Data collection and processing was completed using a Sensors and Software Incorporated pulseEKKO™ Pro SmartCart GPR system and EKKO_Project™ software, respectively. The modelling component was achieved using Schlumberger's Petrel™ E & P software platform, which is tailored to the petroleum industry. The subsurface patterns present in the 2D and 3D models closely matched the cemetery plot plan, validating our data collection, processing, and modelling methods. Both models were adequate for 2D horizontal visualization of reflection patterns at any specific depth. The 3D model was used to identify the presence of a companion burial plot (stacked caskets) and possible leachate plumes below and encircling burial sites, both of which were not evident in the 2D model, highlighting the benefits of 3D modelling when discerning subsurface objects. We expect our findings to be of value to similar GPR studies, with particular significance to geoforensic studies and criminal investigations.


Subject(s)
Burial , Computer Simulation , Forensic Sciences/methods , Radar , Cemeteries , Funeral Rites/history , Geological Phenomena , History, 19th Century , History, 20th Century , Humans , Software
12.
Forensic Sci Int ; 324: 110821, 2021 Jul.
Article in English | MEDLINE | ID: mdl-34000618

ABSTRACT

Bidis are small handmade cigarettes consisting of ~0.2 g of tobacco flakes rolled in a dried leaf of 'Tendu' (Diospyros melanoxylon) or Piliostigma racemosum and tied with a thin thread. They have gained worldwide popularity among smokers and are often collected as forensic DNA evidence from crime scenes and processed similarly to cigarette butts. However, bidi's composition and manufacturing process differs distinctly from the cigarette, and hence the optimal processing for DNA analysis should not be assumed to be similar to cigarette butts. In the present study, the methodical evaluation of the bidi for DNA analysis is reported and an additional process of cell elution from bidi stubs prior to DNA extraction is systematically compared with the direct lysis of bidi stubs which is identical to the standard practice in forensic labs for cigarette butts. In terms of cell recovery from bidi stubs, the SDS based Cell Elution Buffer (CEB) proved to be better than Tween20 based CEB. The three components (cell-elute, supernatant, and processed stub) obtained after the cell elution process of smoked bidi stubs showed varying amounts of DNA. The cell-elute and processed stub exhibited high quality DNA, resulting in 90-100% of the samples giving a full STR profile. On the contrary, the directly lysed stubs yielded high quantity but low quality of DNA, resulting in only 40% of the samples with full STR profiles. The cell elution process enables three components namely cell-elute, supernatant and processed stub from the same bidi to be used for forensic DNA analysis, although the cell-elute proved to be the best source of DNA for STR profiling. The current study demonstrates that the additional cell elution process proved to be an essential step prior to DNA extraction procedure for bidi stubs.


Subject(s)
DNA Fingerprinting , DNA/analysis , Forensic Sciences/methods , Tobacco Products , Cell Separation/methods , Humans , Microsatellite Repeats , Smoking
13.
Forensic Sci Int ; 324: 110826, 2021 Jul.
Article in English | MEDLINE | ID: mdl-34029999

ABSTRACT

This study is a fingerprint comparison of the friction skin detail observed on fingers appearing in ten photographs requested by the Historic Heritage Brigade. These photographs had been uploaded to an online marketplace and show a hand holding different archaeological pieces that had allegedly been stolen. After the ten images had been digitally optimized, seven were determined to contain sufficient clear and continuous ridge detail for the purpose of fingerprint comparison and search. These imprints were compared to the fingerprints of the subject under investigation. Four of them were matched to the index finger, two with the middle finger and one with the ring finger, all from the left hand. These fingerprints were also entered into the Spanish Automated Fingerprint Identification System, resulting in a match to the individual under investigation by the Judicial Police Group.


Subject(s)
Dermatoglyphics , Image Processing, Computer-Assisted , Photography , Crime , Forensic Sciences/methods , Humans , Male
14.
Int J Legal Med ; 135(5): 1983-1991, 2021 Sep.
Article in English | MEDLINE | ID: mdl-33748873

ABSTRACT

The identification of decedents has always been a central issue in forensic pathology, for ethical, criminal, and administrative reasons, but today, it needs more attention due to issues related not only to migration but also to the weakening of family ties. This article presents a descriptive study discussing the Italian regulatory situation developed in the last decade to face the many identification issues, with all its improvements and flaws. Hence, data gathered in 25 years of at the Institute of Legal Medicine of Milan and the epidemiology of unidentified decedents are illustrated. Briefly, from 1995 to 2019, the number of unidentified human remains with no identity or requesting verification of identity amounts to 726, i.e., 3% circa of all autopsies performed at the Institute, with an average of 29 individuals per year. In total, 528 (72.7%) individuals were successfully identified, 100 (13.8%) remained without an identity, and 98 (13.5%) individuals remained with suspected yet unconfirmed identities. Percentages for each identification technique are displayed, with insight into the role of forensic anthropology and odontology compared to genetics, and into the misuse of non-scientific methods allowed by Public Prosecutors. All the data is compared, as much as possible, with the very few recent studies concerning the problem worldwide. Finally, the article aims to show the Italian experience in dealing with unidentified bodies, in order to provide food for thought for other countries toward a discussion regarding a global issue which is sometimes taken for granted and underestimated.


Subject(s)
Body Remains , Cadaver , Forensic Sciences/methods , Identity Recognition , Government Agencies , Humans , Italy/epidemiology , Policy
15.
Med Leg J ; 89(2): 106-116, 2021 Jun.
Article in English | MEDLINE | ID: mdl-33715519

ABSTRACT

Facial reconstruction is an effective forensic technique that can help recreate a victim's facial appearance from the skull. It is typically used to assist law enforcement agencies to identify missing deceased persons. Reconstruction techniques are usually based on the relationship between the underlying hard tissues, such as bone structure, and soft tissues such as the facial muscles and facial features. Facial reconstruction can be a feasible alternative to identify the remains from a decomposed, mutilated, or skeletonised corpse. It is important to remember that although the outcomes are empirical in nature, the technique has been applied widely in many situations. Recent advancements in technology and computer-based techniques have increased the accuracy and validity of this forensic discipline. We consider the most commonly used facial reconstruction techniques in this paper, with a detailed description of manual 3D techniques.


Subject(s)
Face/anatomy & histology , Facial Recognition , Forensic Sciences/methods , Guidelines as Topic , Models, Anatomic , Skull/anatomy & histology , Humans , Specimen Handling
16.
Int J Legal Med ; 135(5): 1965-1981, 2021 Sep.
Article in English | MEDLINE | ID: mdl-33594456

ABSTRACT

Between the ever-increasing availability of surveillance evidence and expert-based forensic facial comparison being considered admissible in court, confirming its validity is paramount. Facial comparison is most commonly conducted using morphological analysis (MA), a largely untested feature-based approach. This study aimed at validating the current recommended practice of MA in both standardised and suboptimal surveillance samples. Face pools of 175 South African males were compiled with a series of facial photographs, using images from the Wits Face Database. The first 75 face pools consisted of wildtype (unstandardised) high-quality target photographs, while the remaining 100 face pools consisted of suboptimal closed-circuit television (CCTV) target images. Target images were compared to high-quality standardised photographs. Face pools were analysed using the Facial Identification Scientific Working Group's guidelines and feature list. Confusion matrices were used to determine the performance of MA in each cohort. MA was found highly accurate (chance-corrected accuracy (CCA): 99.1%) and reliable (κ = 0.921) in the photographic sample and less accurate (CCA: 82.6%) and reliable (κ = 0.743), in the CCTV sample. Higher false-positive and false-negative rates were noted for the CCTV sample, with the majority of errors resulting in false-negative outcomes. The decreased performance in the CCTV sample was attributed to various factors including image quality, angle of recording and lighting. Other studies testing facial comparison identified lower accuracies and reliability across various conditions. Better performance was found here and in other studies that included some form of facial feature list, reinforcing the importance of using a systematic facial feature list.


Subject(s)
Facial Recognition , Forensic Sciences/methods , Guidelines as Topic/standards , Photography , Television , Video Recording , Adult , Databases, Factual , Humans , Male , Predictive Value of Tests , Sensitivity and Specificity , South Africa
17.
PLoS One ; 16(2): e0246645, 2021.
Article in English | MEDLINE | ID: mdl-33600430

ABSTRACT

The purpose of this study was to explore the speaker-discriminatory potential of vowel formant mean frequencies in comparisons of identical twin pairs and non-genetically related speakers. The influences of lexical stress and the vowels' acoustic distances on the discriminatory patterns of formant frequencies were also assessed. Acoustic extraction and analysis of the first four speech formants F1-F4 were carried out using spontaneous speech materials. The recordings comprise telephone conversations between identical twin pairs while being directly recorded through high-quality microphones. The subjects were 20 male adult speakers of Brazilian Portuguese (BP), aged between 19 and 35. As for comparisons, stressed and unstressed oral vowels of BP were segmented and transcribed manually in the Praat software. F1-F4 formant estimates were automatically extracted from the middle points of each labeled vowel. Formant values were represented in both Hertz and Bark. Comparisons within identical twin pairs using the Bark scale were performed to verify whether the measured differences would be potentially significant when following a psychoacoustic criterion. The results revealed consistent patterns regarding the comparison of low-frequency and high-frequency formants in twin pairs and non-genetically related speakers, with high-frequency formants displaying a greater speaker-discriminatory power compared to low-frequency formants. Among all formants, F4 seemed to display the highest discriminatory potential within identical twin pairs, followed by F3. As for non-genetically related speakers, both F3 and F4 displayed a similar high discriminatory potential. Regarding vowel quality, the central vowel /a/ was found to be the most speaker-discriminatory segment, followed by front vowels. Moreover, stressed vowels displayed a higher inter-speaker discrimination than unstressed vowels in both groups; however, the combination of stressed and unstressed vowels was found even more explanatory in terms of the observed differences. Although identical twins displayed a higher phonetic similarity, they were not found phonetically identical.


Subject(s)
Speech Acoustics , Speech/physiology , Verbal Behavior/physiology , Acoustics , Adult , Brazil , Forensic Sciences/methods , Humans , Language , Male , Phonetics , Psychoacoustics , Speech Perception/physiology , Twins, Monozygotic
18.
Forensic Sci Int ; 320: 110702, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33561789

ABSTRACT

Considering the widespread use of mobile phones, audio recordings of crime scenes are widely used as digital evidence; however, it is important to authenticate the audio recordings before consideration as legal evidence. This study aimed to develop a method to authenticate audio recordings generated using the iPhone through three steps: 1) bitrate/audio latency time analysis of audio recordings, 2) comparison of the file structure/timestamp on audio recordings, and 3) device-based log history examinations for the provenance of audio recordings. Herein, we analyzed audio recording samples from ten different models of mobile handsets of the iPhone with Advanced Audio Coding (AAC) or Apple Lossless Audio Codec (ALAC), through the Voice Memos application depending on the iPhone Operating System (iOS). To analyze the characteristics of these audio recordings, we compared features including audio latency, file format/structure, and timestamps between the audio recordings generated in the iPhone and those edited through the built-in audio editing function. Furthermore, we investigated the log history registered in devices during the generation of the audio recordings. Differences in the audio latency, file size, timestamps, bitrate, and log history were confirmed on the iPhone when manipulating the audio recordings. The present results show that it is possible to verify the authentication of audio recordings generated using the Voice Memos application on iPhone.


Subject(s)
Forensic Sciences/methods , Mobile Applications , Smartphone , Voice , Humans , Sound Spectrography
19.
Forensic Sci Int ; 320: 110710, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33561790

ABSTRACT

Bayesian networks have shown to be a useful tool for the evaluation of forensic findings given activity level propositions. In this paper, we demonstrate how case specific experiments can be used to assign probabilities to the states of the nodes of a Bayesian network for the evaluation of fingermarks given activity level propositions. The transfer, persistence and recovery of fingermarks on knives is studied in experiments where a knife is either used to stab a victim or to cut food, representing the activities that were disputed in the case of the murder of Meredith Kercher. Two Bayesian networks are constructed, exploring the effect of different uses of the experimental data by assigning the probabilities based on the results of the experiments. The evaluation of the findings using the Bayesian networks demonstrates the potential for fingermarks in addressing activity level propositions.


Subject(s)
Bayes Theorem , Dermatoglyphics , Forensic Sciences/methods , Weapons , Female , Humans , Wounds, Stab
20.
Forensic Sci Int ; 320: 110701, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33581656

ABSTRACT

The sensitivity of imaging spectroscopy to haemoglobin derivatives makes it a promising tool for detecting blood. However, due to complexity and high dimensionality of hyperspectral images, the development of hyperspectral blood detection algorithms is challenging. To facilitate their development, we present a new hyperspectral blood detection dataset. This dataset, published under an open access license, consists of multiple detection scenarios with varying levels of complexity. It allows to test the performance of Machine Learning methods in relation to different acquisition environments, types of background, age of blood and presence of other blood-like substances. We have explored the dataset with blood detection experiments, for which we have used a hyperspectral target detection algorithm based on the well-known Matched Filter detector. Our results and their discussion highlight the challenges of blood detection in hyperspectral data and form a reference for further works.


Subject(s)
Blood Stains , Datasets as Topic , Forensic Sciences/methods , Hyperspectral Imaging , Algorithms , Humans , Likelihood Functions , Machine Learning
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