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

Author(s)

Fonseca, Aline C. S. ^[1] ; Pereira, Jose F. Q. ^{[2, 1]} ; Honorato, Ricardo S. ^[3] ; Bro, Rasmus ^[4] ; Pimentel, Maria Fernanda ^[5]

Affiliation

^[1] Univ Fed Pernambuco, Dept Fundamental Chem, Av Jornalista Anibal Fernandes, BR-50740560 Recife, PE - Brazil

^[2] Univ Estadual Campinas, Inst Chem, POB 6154, BR-13083970 Campinas, SP - Brazil

^[3] Fed Police, Cais Apolo 321, BR-50030907 Recife, PE - Brazil

^[4] Univ Copenhagen, Dept Food Sci, Rolighedsvej 26, DK-1958 Frederiksberg - Denmark

^[5] Univ Fed Pernambuco, Dept Chem Engn, Av Economistas, Cidade Univ S-N, BR-50740590 Recife, PE - Brazil

• Document type: Journal article
• Source: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY; v. 267, n. 1 FEB 15 2022.
• Web of Science Citations: 0

Abstract

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. (c) 2021 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 08/57808-1 - National Institute of Advanced Analytical Science and Technology
• Grantee: Celio Pasquini
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/50951-4 - INCT 2014: Advanced Analytical Technologies
• Grantee: Celio Pasquini
• Support Opportunities: Research Projects - Thematic Grants