Visualization of Methamphetamine-Contaminated Fingermarks on Glass Surfaces by Field Emission Scanning Electron Microscope for Forensic Investigation

Background:Fingermark is an individual’s primary identification source.It is helpful in determining individuals involved in illegal activities and is frequently encountered in clandestine laboratories.During forensic investigation,the critical question to be answered is whether a fingermark was left on a surface before or after the initiation of an unlawful activity.Aims and Objectives:This study aimed to investigate the visualization of methamphetamine-contaminated fingermarks on glass surfaces and estimate the immediacy of their depositions.Materials and Methods:In this study,the prior-deposition contaminated fingermarks,i.e.,fingermarks deposited a surface priorly contaminated by methamphetamine,and the postdeposition contaminated fingermarks,i.e.,fingermarks deposited on a clean surface but subsequently contaminated with methamphetamine were visualized and compared using Field Emission Scanning Electron Microscope(FESEM).Results:Under FESEM,the latent fingermarks and the crystalline structure of methamphetamine were clearly visualized.The postdeposition contaminated fingermarks appeared in smudge conditions in all the three replicate samples,where the ridge and nonridge areas could not be well-distinguished.On the contrary,the prior-deposition contaminated fingermark demonstrated distinct separations between ridges and nonridges.However,the application of fingerprint powders reduced the possibility to determine the immediacy of deposition.Conclusion:To conclude,both prior-deposition contaminated fingermarks and postdeposition contaminated fingermarks can be discriminated,providing information on the instance when a fingermark was left on a surface.

Distinctive Bullet Impact Holes by 9‑mm Caliber Projectile on Sheet Metal Surfaces

Introduction:A comprehensive scene reconstruction requires forensic investigators to examine the impact marks left on various surfaces to identify whether a projectile produces a specific hole.Subsequently,it is further necessary to determine whether a particular ammunition has caused the impact.Throughout history,designs of ammunition have evolved with the intended effects,which could leave different impact marks on a target surface,especially by ammunition with a nonconventional design.Careful examination on impact marks and determination of their specific characteristics on sheet metal of vehicle would provide crucialforensic information.Aim:This study was aimed to physically characterize bullet impact holes made by 11 types of 9-mm caliber ammunitions.Materials and Methods:Two automotive doors were shot with different ammunitionsfrom the same firearm,and the morphological features of bullet impact holes were observed and compared.Results:Bullet impact holes produced by the various ammunitions could be differentiated through careful observation of bullet hole circumferences,presence of petalling effect,metallic ring and triangular peak at the edge,and deposition of residue at the peripheral area of bullet impact holes.Ammunitions with nonconventional design such as Inceptor‑Polycase and GECO Hexagon showed observable morphological differences and discriminated them from bullet impact holes made by conventional ammunitions.Conclusion:A thorough physical examination could aid in distinguishing bullet impact holes and predicting the possible types of ammunition that had made an impact hole on a surface.