TY - JOUR

T1 - Hierarchical classification models and Handheld NIR spectrometer to human blood stains identification on different floor tiles

AU - Fonseca, Aline C.S.

AU - Pereira, José F.Q.

AU - Honorato, Ricardo S.

AU - Bro, Rasmus

AU - Pimentel, Maria Fernanda

N1 - Funding Information: The authors would like to acknowledge the N?cleo de Qu?mica Anal?tica Avan?ada de Pernambuco - NUQAAPE (FACEPE grants APQ-0346-1.06/14), N?cleo de Estudos em Qu?mica Forense - NEQUIFOR (CAPES grants AUXPE 3509/2014), CNPq (grants 428891/2018-7), Instituto Nacional de Tecnologias Anal?ticas Avan?adas - INCTAA (CNPq grants 573894/2008-6 and 465768/2014-8 and FAPESP grants 2008/57808-1 and 2014/50951-4). The English text of this paper has been revised by Sidney Pratt, Canadian, MAT (The Johns Hopkins University), RSAdip - TESL (Cambridge University). Funding Information: The authors would like to acknowledge the Núcleo de Química Analítica Avançada de Pernambuco - NUQAAPE (FACEPE grants APQ-0346-1.06/14), Núcleo de Estudos em Química Forense - NEQUIFOR (CAPES grants AUXPE 3509/2014), CNPq (grants 428891/2018-7), Instituto Nacional de Tecnologias Analíticas Avançadas - INCTAA (CNPq grants 573894/2008-6 and 465768/2014-8 and FAPESP grants 2008/57808-1 and 2014/50951-4). Publisher Copyright: © 2021 Elsevier B.V.

PY - 2022

Y1 - 2022

N2 - One of the most important types of evidence in certain criminal investigations is traces of human blood. For a detailed investigation, blood samples must be identified and collected at the crime scene. The present study aimed to evaluate the potential of the identification of human blood in stains deposited on different types of floor tiles (five types of ceramics and four types of porcelain tiles) using a portable NIR instrument. Hierarchical models were developed by combining multivariate analysis techniques capable of identifying traces of human blood (HB), animal blood (AB) and common false positives (CFP). The spectra of the dried stains were obtained using a portable MicroNIR spectrometer (Viavi). The hierarchical models used two decision rules, the first to separate CFP and the second to discriminate HB from AB. The first decision rule, used to separate the CFP, was based on the Q-Residual criterion considering a PCA model. For the second rule, used to discriminate HB and AB, the Q-Residual criterion were tested as obtained from a PCA model, a One-Class SIMCA model, and a PLS-DA model. The best results of sensitivity and specificity, both equal to 100%, were obtained when a PLS-DA model was employed as the second decision rule. The hierarchical classification models built for these same training sets using a PCA or SIMCA model also obtained excellent sensitivity results for HB classification, with values above 94% and 78% of specificity. No CFP samples were misclassified. Hierarchical models represent a significant advance as a methodology for the identification of human blood stains at crime scenes.

AB - One of the most important types of evidence in certain criminal investigations is traces of human blood. For a detailed investigation, blood samples must be identified and collected at the crime scene. The present study aimed to evaluate the potential of the identification of human blood in stains deposited on different types of floor tiles (five types of ceramics and four types of porcelain tiles) using a portable NIR instrument. Hierarchical models were developed by combining multivariate analysis techniques capable of identifying traces of human blood (HB), animal blood (AB) and common false positives (CFP). The spectra of the dried stains were obtained using a portable MicroNIR spectrometer (Viavi). The hierarchical models used two decision rules, the first to separate CFP and the second to discriminate HB from AB. The first decision rule, used to separate the CFP, was based on the Q-Residual criterion considering a PCA model. For the second rule, used to discriminate HB and AB, the Q-Residual criterion were tested as obtained from a PCA model, a One-Class SIMCA model, and a PLS-DA model. The best results of sensitivity and specificity, both equal to 100%, were obtained when a PLS-DA model was employed as the second decision rule. The hierarchical classification models built for these same training sets using a PCA or SIMCA model also obtained excellent sensitivity results for HB classification, with values above 94% and 78% of specificity. No CFP samples were misclassified. Hierarchical models represent a significant advance as a methodology for the identification of human blood stains at crime scenes.

KW - Classification

KW - Crime scenes

KW - Handheld spectrometer

KW - Hierarchical model

KW - Human blood stains

KW - Near infrared

U2 - 10.1016/j.saa.2021.120533

DO - 10.1016/j.saa.2021.120533

M3 - Journal article

C2 - 34749108

AN - SCOPUS:85118589898

VL - 267

JO - Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

JF - Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

SN - 1386-1425

M1 - 120533

ER -