Verma Neha, Sharma Vishal, Kumar Raj, Sharma R, Joshi M C, Umapathy G R, Ohja Sunil, Chopra Sundeep
Institute of Forensic Science and Criminology, Panjab University, Chandigarh, 160014, India.
DFSS Fellow, Central Forensic Science Laboratory (Document Division), Chandigarh, 160036, India.
Anal Bioanal Chem. 2019 Jun;411(16):3477-3495. doi: 10.1007/s00216-019-01824-z. Epub 2019 May 15.
The detection of computer-generated document forgeries has always been a challenging task for forensic document examiners (FDE). With the aim to support the examination processes, Schottky field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FE-SEM-EDS) is explored as a recent tool to analyze black toners obtained from laser printers and photocopier machines. Forty samples each from the laser printer and photocopier machines are procured and studied for morphological features, elemental profile, and multivariate analysis. The acquired SEM images and spectra are evaluated to discriminate and classify the toners having a different source of origin. Multivariate analysis is applied to develop a model of classification to successfully classify the printed documents on the basis of the similarities and differences in their composition. Hierarchical cluster analysis (HCA) discriminates the printouts in the forms of groups based on their chemical composition. The laser printer and the photocopier printed documents are grouped into 11 and eight clusters, respectively, based on their elemental composition. Cross-validation is further conducted to assess the capabilities of developed principal component analysis (PCA) and linear discriminant analysis (LDA) models for the examination of printouts from unknown origin. Graphical abstract.
对于法医文件检验人员（FDE）而言，检测计算机生成的文件伪造品一直是一项具有挑战性的任务。为了支持检验过程，人们探索将带有能量色散X射线光谱仪的肖特基场发射扫描电子显微镜（FE-SEM-EDS）作为一种最新工具，用于分析从激光打印机和复印机获取的黑色墨粉。从激光打印机和复印机中分别采集了40个样本，并对其形态特征、元素分布和多变量分析进行了研究。对获取的扫描电子显微镜图像和光谱进行评估，以区分和分类具有不同来源的墨粉。应用多变量分析来建立一个分类模型，以便根据打印文件组成的异同成功地对其进行分类。层次聚类分析（HCA）根据打印输出的化学成分将其以组的形式区分开来。基于元素组成，激光打印机和复印机打印的文件分别被分为11个和8个聚类。进一步进行交叉验证，以评估所开发的主成分分析（PCA）和线性判别分析（LDA）模型对检验未知来源打印输出的能力。图形摘要。
