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[Display omitted] • ATR-FTIR spectroscopy was used to distinguish 3 wild cats from black guard hair. • The PLS-DA model successfully classified three species into distinct groups. • The PLS-DA model successfully differentiated human and non-human hair. • 100 % accuracy was achieved during the blind test. Hair is a commonly encountered trace evidence in wildlife crimes involving mammals and can be used for species identification which is essential for subsequent judicial proceedings. This proof of concept study aims, to distinguish the black guard hair of three wild cat species belonging to the genus Panthera i.e. Royal Bengal Tiger (Panthera tigris tigris), Indian Leopard (Panthera pardus fusca), and Snow Leopard (Panthera uncia) using a rapid and non-destructive ATR-FTIR spectroscopic technique in combination with chemometrics. A training dataset including 72 black guard hair samples of three species (24 samples from each species) was used to construct chemometric models. A PLS2-DA model successfully classified these three species into distinct classes with R-Square values of 0.9985 (calibration) and 0.8989 (validation). VIP score was also computed, and a new PLS2DA-V model was constructed using variables with a VIP score ≥ 1. External validation was performed using a validation dataset including 18 black guard hair samples (6 samples per species) to validate the constructed PLS2-DA model. It was observed that PLS2-DA model provides greater accuracy and precision compared to the PLS2DA-V model during cross-validation and external validation. The developed PLS2-DA model was also successful in differentiating human and non-human hair with R-Square values of 0.99 and 0.91 for calibration and validation, respectively. Apart from this, a blind test was also carried out using 10 unknown hair samples which were correctly classified into their respective classes providing 100 % accuracy. This study highlights the advantages of ATR-FTIR spectroscopy associated with PLS-DA for differentiation and identification of the Royal Bengal Tiger, Indian Leopard, and Snow Leopard hairs in a rapid, accurate, eco-friendly, and non-destructive way. [ABSTRACT FROM AUTHOR]

Sealing wax is used for maintaining the integrity and authenticity of a document or physical evidence. Any tampering with the seal calls into question the overall integrity and authenticity of the tangible evidence or document. In these circumstances, determining the authenticity of the sealing material (physical and chemical) becomes imperative. In this study, ATR‐FTIR spectroscopy supported by chemometrics has been used to differentiate sealing wax samples belonging to 12 different brands available across India. All the samples were first melted, cooled, and then analyzed using ATR‐FTIR spectroscopy in the mid‐infrared region (4000–600 cm−1). The obtained spectra were first examined visually for the presence of different functional groups. Principal component analysis (PCA) and principal component analysis‐linear discriminant analysis (PCA‐LDA) were employed to analyze the sample clustering patterns and to categorize them into their respective groups, respectively. For classification, a PCA‐LDA training model was applied, and it demonstrated 95.83% accuracy. The validation test resulted in an accuracy of 83.33%. PCA‐LDA model offered 100% accurate prediction for samples on various substrates, including cloth, cardboard, and paper. A blind study was also performed using five unknown samples, which were accurately classified into their respective groups. PCA‐LDA model will be helpful in providing investigative leads by linking a questioned sealing wax sample with its respective group. [ABSTRACT FROM AUTHOR]

Lip balm may be encountered as physical evidence in cases involving sexual assaults, homicides, and kidnappings. Lip balm can be used as corroborative evidence by providing a potential link between the victim, accused, and the crime scene. For lip balms to be used as evidence, it is important to understand the diversity and their aging process under different conditions. Therefore, in this study, ATR‐FTIR spectroscopy in conjunction with chemometric tools such as principal component analysis (PCA) and linear discriminant analysis (LDA) has been used for the objective identification and differentiation of 20 brands of lip balms. Moreover, lip balms on different substrates and wearing effects over time were also investigated. The results show that the PCA‐LDA training accuracy was 92.5%, whereas the validation accuracy comes out to be 83.33%. A blind study using pristine samples was also performed which resulted in 80% PCA‐LDA accuracy. PCA‐LDA prediction of samples on various substrates showed a higher chemometric prediction accuracy for nonporous substrates (glass, plastic, and steel), than for porous substrates (cotton cloth, cotton swab stick, dry tissue paper, and white paper) for samples kept in room temperature and under sunlight for 15 days. The substrate study showed that the samples from various substrates could effectively generate respective spectra which can help in brand‐level identification even after several days. The present method demonstrates a potential for lip balm samples to be used in forensic casework applications. [ABSTRACT FROM AUTHOR]

Forensic investigation of cases involving spray paints requires comparison of paint such as those recovered from graffiti with the references sample seized from the suspect's possession site. This study describes the use of Attenuated Total Reflectance Fourier Transform Infrared (ATR‐FT‐IR) spectroscopy for nondestructive analysis of 20 red spray paints of different manufactures, which could be encountered at a crime scene, particularly in case of vandalism. Spray paints could be encountered on a number of different substrates, and therefore, the samples were placed on simulated substrates and were analyzed in order to check the effect of substrates on sample analysis. Results showed that all samples could be successfully differentiated using ATR‐FT‐IR spectroscopy assisted with principal component analysis. Analysis of spray paints on a paper and fabric substrate resulted in poor spectra and hampered the comparative examination between the spray paint deposited on fabric/paper surface and the control sample. In case of sample deposited on cemented wall, the substrate got scraped out along with the sample and caused interferences in the spectrum. On the other hand, for sample deposited on the floor, gloves, metal, plastic, leather shoes, tile, wood, and hair substrates, all the significant peaks were observed to be present and hence it was concluded that comparative studies can be done between neat spray paint and spray paint deposited on the aforesaid substrates. Additionally, blind validation test was conducted and it resulted in linking the blind samples with the source or origin with 100% accuracy. [ABSTRACT FROM AUTHOR]

Trace nail polish evidence recovered in forensic investigations can serve as important corroborative evidence and assist in crime reconstruction, especially in cases related to physical and sexual assault against women. Nevertheless, nail polish evidence has been neglected either owing to its infrequent occurrence or, when it is encountered, it is present in only a trace quantity, which makes the analysis difficult when using conventional techniques. In this study, ATR-FTIR spectroscopy has been employed for the analysis of 19 brands of nail polish with 73 different series (similar shades). The spectra obtained using this technique have been interpreted statistically using PCA and Correlation Coefficient methods with discriminating powers of 99.5% and 99.3% respectively. The spectrum of nail polish showed various functional groups: aliphatic amine, aliphatic and aromatic nitro groups of nitrocellulose, alcohol, acid, and aromatic ester. In addition, peaks of alkyne groups indicative of talc or mica compounds were also observed. The current research methodology effectively differentiated almost all the samples and has the prospect of potential application in future forensic casework. [ABSTRACT FROM AUTHOR]

Differentiation and identification of Royal Bengal Tiger (Panthera tigris tigris) and Indian Leopard (Panthera pardus fusca) claws is a challenging task in wildlife forensics, due to similarity in their morphology, anatomy and chemical compositions as both the species are closely related to each other genetically. ATR-FTIR spectroscopy, which offers a non-destructive and safe alternative technique to other conventional methods, has been employed in the present work to differentiate claws of Royal Bengal Tiger and Indian Leopard. An attempt has been made to differentiate 31 reference claw samples from 16 different Royal Bengal Tigers, 15 different Indian Leopards, and 10 fake claws using ATR-FTIR spectroscopy supplemented with PCA, PLS-DA, and LDA. PCA could not distinguish the samples of two closely related species among themselves as well as from the fake claws. On the other hand, PLS-DA and LDA models both yielded highly significant classification rate for differentiation among the samples of Royal Bengal Tiger, Indian Leopard, and their fake counterparts. Further, seven blind claw samples that were pretended to be unknown to the analyst of both the species are also examined and identified correctly to their respective groups. The R-Square value obtained for PLS-DA model to differentiate Royal Bengal Tiger, Indian Leopard, and fake claws is 0.99, which is highly significant for predictive accuracy. This study shows that ATR-FTIR spectroscopy with PLS-DA/LDA has a potential to present a rapid, non-destructive, reliable, and eco-friendly approach for the accurate identification and differentiation of Royal Bengal Tiger and Indian Leopard claws. Unlabelled Image • First study to differentiate Tiger and Leopard claws by ATR-FTIR and Chemometrics • Differentiated with 100% accuracy from each other and from their fake counterparts • Blind claw samples of both the species are also examined and identified correctly. • FTIR with chemometrics presents a non-destructive alternative to existing methods. [ABSTRACT FROM AUTHOR]