Background:Determining the chronological sequence at print-handwriting intersections remains a persistent challenge in forensic document examination.Methods:In this study,we developed a coaxial light microscopy approa...Background:Determining the chronological sequence at print-handwriting intersections remains a persistent challenge in forensic document examination.Methods:In this study,we developed a coaxial light microscopy approach based on a six-feature taxonomy to assess stroke order.A total of 3600 intersections were prepared under two scenarios-handwriting-before-printing and printing-before-handwriting-using three types of laser printers and twelve commercial pens.Six morphological features were systematically evaluated:Internal ink loss,gloss reduction,stroke contraction,central bright trace,edge ink loss,and stroke deformation.Results:In handwriting-before-printing samples,gloss reduction and internal ink loss were the most prominent indicators,whereas central bright trace emerged as the key feature in printing-beforehandwriting samples.Significant differences were observed across printer classes and pen families,with loose-toner printers and rollerball/ballpoint pens yielding clearer feature expression than fused-toner printers and fiber-tip pens.Temporal testing at 0 and 30 days showed that gloss reduction,stroke contraction,central bright trace,and stroke deformation were time-robust,while internal ink loss and edge ink loss exhibited greater variability.Conclusion:In a blinded case validation,three independent examiners reached unanimous conclusions using the taxonomy.These findings demonstrate that coaxial light microscopy provides a reproducible and accessible method for establishing stroke sequence at print-handwriting intersections,with clear potential for forensic application.展开更多
文摘Background:Determining the chronological sequence at print-handwriting intersections remains a persistent challenge in forensic document examination.Methods:In this study,we developed a coaxial light microscopy approach based on a six-feature taxonomy to assess stroke order.A total of 3600 intersections were prepared under two scenarios-handwriting-before-printing and printing-before-handwriting-using three types of laser printers and twelve commercial pens.Six morphological features were systematically evaluated:Internal ink loss,gloss reduction,stroke contraction,central bright trace,edge ink loss,and stroke deformation.Results:In handwriting-before-printing samples,gloss reduction and internal ink loss were the most prominent indicators,whereas central bright trace emerged as the key feature in printing-beforehandwriting samples.Significant differences were observed across printer classes and pen families,with loose-toner printers and rollerball/ballpoint pens yielding clearer feature expression than fused-toner printers and fiber-tip pens.Temporal testing at 0 and 30 days showed that gloss reduction,stroke contraction,central bright trace,and stroke deformation were time-robust,while internal ink loss and edge ink loss exhibited greater variability.Conclusion:In a blinded case validation,three independent examiners reached unanimous conclusions using the taxonomy.These findings demonstrate that coaxial light microscopy provides a reproducible and accessible method for establishing stroke sequence at print-handwriting intersections,with clear potential for forensic application.
