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Automobile glass forensics using suitable chemical analysis techniques is an important field in forensic science. In this respect, major elements help to classify the glass samples, whereas trace elements in conjunction with chemometrics are very important to help in grouping for source/origin finding. Five different radioanalytical techniques namely scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDX), energy dispersive X-ray fluorescence (ED-XRF), particle induced gamma-ray/X-ray emission (PIGE/PIXE), and instrumental neutron activation analysis (INAA) were utilized for chemical characterization of automobile (car) windshield glasses and the results have been discussed for possible forensic applications. Methods were validated by analyzing geological and glass-certified/standard reference materials. The R&D work was carried out for 48 real case car windshield glass samples from 10 different manufacturers, whereas the method was standardized for 5 glasses, then applied to 20, and finally to 48 glass samples. From the results of all techniques, it was observed that trace elements like Sc, Cr, Co, Mn, Hf, Ta, Ba La, Ce, Sm, Eu, Yb, and Th obtained by INAA are very helpful for the grouping. Preliminary grouping of the first five samples was carried out utilizing concentration ratios with respect to Sc, La/Ce, and total rare earth elements (REEs) as well as from biplots and ternary plots. External (in air) PIGE and INAA methods were optimized and applied to "as received" glass fragments for confirming the class of glass from major elements and grouping study from trace elements, respectively. Different clustering and grouping methods of chemometrics like cluster analysis (CA) and principal component analysis (PCA) were employed to get the best grouping of similar glasses. PCA using trace elemental concentration was found to be the best approach. Final grouping confirmation of 48 automobile glasses was carried out by PCA, which indicated a clear nine groups from nine branded manufacturers, whereas one set of local glasses did not show any group. The study showed the efficacy of external PIGE and INAA for the classification and grouping study of these soda lime glasses and trace elements in conjunction with PCA for confirmation of grouping needed for forensic applications. [ABSTRACT FROM AUTHOR]

Abstract The potential to ascertain the origin and aging of bloodstains have various important applications in the forensic serological investigation. The individualization of bloodstain is necessary as both human and animals can be involved in the crimes. The foremost advantages of these types of investigation are: the expert significantly differentiates between human and animal blood which ultimately helps in the decipherment of criminal associated with the crimes; the aging of bloodstain assists in the determination of approximate time and date of incidence of crime. In recent time, significant advancement in analytical methods has been done to investigate the complex evidence collected from crime scene such as bloodstain. Along with modern analytical methods, the multivariate methods are also obtaining popularity in forensic science, especially in the bloodstain investigations. This review emphasizes the importance of analytical and chemometric models that have been utilized for the identification and aging of bloodstains. The reliability and sensitivity of these models are compared. Highlights • Advanced analytical and chemometric methods for bloodstain investigation are summarized. • Most of the studies utilized spectroscopy methods especially Raman and FTIR. • PLS-DA and regression-based modeling have been widely used for discrimination and dating studies. • New models like SVM and ANN provide better results than PLS-DA in discrimination as well as aging. [ABSTRACT FROM AUTHOR]

This review represents a detailed discussion of the multivariate methods used in the examination of forensic exhibits; their advantages, disadvantages, and efficiency are compared. The last decade has seen the application of the chemometric methods combined with analytical techniques for characterization and discrimination of samples, which leads to the informative and representative examinations of the samples. Many research articles with reference to the use of chemometrics in forensic science have been published. This review has been divided into various sections which include chemometrics, its history, multivariate methods, and the application of chemometrics in various disciplines of forensic science. It is suggested that these new techniques and mathematical/statistical methods should be utilized in forensic science casework to get statistical confidence in the results. [ABSTRACT FROM AUTHOR]

[Display omitted] • Forensic investigations favour quick and non-destructive identification and discrimination. • Machine learning techniques combined with ATR-FTIR become more prevalent as a way to enhance the precision of the measure. • 220 samples of rubber residues from automobile tyres from different brands had been distinguished. • 15 machine learning approaches have been explored for tyre brand discrimination and type of vehicle identification from rubber residues. • The Extra Tree Classifier outperforms other ML classifiers, in accordance with the outcome of this research. Criminal instances involving collision accidents, hit-and-run incidents, abduction, hostage-taking, and the unauthorised transit of forbidden items generally include evidence involving rubber traces from automobile tyres. These traces can be located on the road surface, in clothing, on the victim(s) themselves, or on items as skid marks following sudden stopping and spinning around. These traces serve as crucial evidence by reducing the range of suspects by revealing linkages between the getaway vehicle, the site of the crime, and the perpetrator through the tyre's brand, producer, or origin. This study offered a way for classifying 220 tyre rubber samples from different brands using various machine learning algorithms in PyCaret in conjunction with rapid and non-destructive ATR-FTIR spectroscopy equipped with diamond crystal. On spectral information from ATR-FTIR, pre-processing tools such as baseline correction, smoothing, derivatization, and normalisation were also implemented prior to machine learning. This approach has the potential to be advantageous for efficiently and non-destructively identifying rubber traces as forensic evidence and for facilitating brand recognition of automobile tyres. [ABSTRACT FROM AUTHOR]

Cosmetic products such as sunscreens may often be encountered in forensic investigations as traces left on tissue paper, apparels, drinkware, painted exterior, or various alternative surfaces. The pilot study aimed at efficiently using Infrared spectroscopy coupled with chemometrics to cater to unbiased, rapid, and non-destructive identification of sunscreens which will aid various forensic investigations soon. In the present research, a total of 109 sunscreen samples were analyzed using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. The physicochemical data from the FTIR instrument was then subjected to principal component analysis (PCA), which successfully distinguished most of the samples based on their spectral information. The trained model resulted in clear segregation of unknown sunscreen samples. This could provide an outstanding level of confidence during the conduction of 'questioned versus known' comparisons of similar sunscreens and will give the details of the manufacturer, thereby, helping in rounding off the suspects. Unlabelled Image • 109 sunscreen samples were analyzed using ATR-FTIR & Chemometric methods. • No prior sample preparation needed for the devised method of characterization. • The trained model was validated using unknown samples. • The trained model resulted in discrimination accuracies to 100%. • First such study on sunscreen stains identification utilizing IR and Chemometric methods. [ABSTRACT FROM AUTHOR]

Kajal, also known as Kohl (Arabic name) a cosmetic, is used for the beautificationof eyes and face as a whole. It can serve as an important corroborative evidence in various crimes against women and can also be used as a writing instrument to write the anonymous letters, threatening notes, suicide letters on a variety of substrates such as cotton cloth, tissue paper, tissue wipes, skin etc. 40 Kajal samples from 33 different brands were collected and analyzed using Attenuated Total Reflectance Fourier Transform Infrared (ATR FT-IR) Spectroscopy with advance statistical and computational tools. The present research investigated the application of this technique for the differentiation of locally manufactured Kajal based on the differences in the peak patterns, frequencies, and strengths of peak exhibited within the fingerprint region. The blind test was conducted with four unknown samples which were pretended to be unknown to the analyst and it was observed that all the unknown samples were predicted correctly with their respective classes. Effect of substrates and ageing were also studied under similar set of experimental conditions. This technique has been proven to be of high significance with complete non-destructive nature requiring minimal or no sample preparation and high repeatability. [ABSTRACT FROM AUTHOR]