A comprehensive review on application of atomic force microscopy in Forensic science.

The primary objective of forensic investigation of a case is to recognize, identify, locate, and examine the evidence. Microscopy is a technique that provides crucial information for resolving a case or advancing the investigation process by analyzing the evidence obtained from a crime scene. It is often used in conjunction with suitable analytical techniques. Various microscopes are employed; scanning probe microscopes are available in diverse forensic analyses and studies. Among these, the atomic force microscope (AFM) is the most commonly used scanning probe technology, offering a unique morphological and physico-chemical perspective for analyzing multiple pieces of evidence in forensic investigations. Notably, it is a non-destructive technique capable of operating in liquid or air without complex sample preparation. The article delves into a detailed exploration of the applications of AFM in the realms of nanomechanical forensics and nanoscale characterization of forensically significant samples.

Grain-surface microtextures in deposits affected by periglacial conditions (Abalakh High-Accumulation Plain, Central Yakutia, Russia).

Our paper describes and interprets grain microtexture and microstructure collected from periglacial sediments on the Abalakh High-Accumulation Plain (AHAP) in Central Yakutia. This territory occupies the Lena-Amga Rivers interfluve. In borehole 18/1, five sediment Complexes (I-V) of successive environments were recognized: 1) alluvial in the base of the borehole-Complex I; 2) alluvial-lake-Complex II; 3) lake-complex-Complex III; 4) ice-complex (yedoma)-Complex IV; and finally 5) a Holocene cover-Complex V. Quartz sand-grain and silt-grain microtextural analysis was undertaken in a scanning electron microscope (SEM) and supplemented by mineralogical analyses to reconstruct the sedimentary-accumulation environment, discern the influence of periglacial conditions on the grains, and identify the sediment source(s) for each complex. Based on the results, a conclusion can be reached that the accumulation of Complex I took place as a result of multiple repetitive transportation events recycling the same material and introducing a limited supply of new material into the fluvial environment. Upward in the succession, fluvial-process activities decreased in favour of lake-deposit accumulation. Frozen syngenetic ice-rich silty deposits-yedoma or ice complex-of Complex IV are composed of grains with a precipitated surface, but differ from the underlying deposits in the degree of crusting and mineralogy. Most probably aeolian processes are responsible for their transport. They include a variety of sediments, including older-sourced sediments such as retransported loess and the detritus from mechanical weathering coeval with sediment accumulation. Traces of frost and chemical weathering have been identified on the grain surfaces, the former visible in the form of breakage blocks and conchoidal fracture microtextures and the latter - as surface crusting. However, the frequencies of these microtextures are low, which suggests a relatively high rate of sediment accumulation.

Journey history reconstruction from the soils and sediments on footwear: An empirical approach.

The value of environmental evidence for reconstructing journey histories has significant potential given the high transferability of sediments and the interaction of footwear with the ground. The importance of empirical evidence bases to underpin the collection, analysis, interpretation and presentation of forensic trace materials is increasingly acknowledged. This paper presents two experimental studies designed to address the transfer and persistence of sediments on the soles of footwear in forensically relevant scenarios, by means of quartz grain surface texture analysis, a technique which has been demonstrated to be able to distinguish between samples of mixed provenance. It was identified that there is a consistent trend of transfer and persistence of sediments from hypothetical pre-, syn- and post-crime event locations across the sole of the shoe, with sediments from 'older' locations likely to be retained in small proportions. Furthermore, the arch of the shoe (the area of lowest foot pressure distribution) typically (but not exclusively) retained the highest proportion of grain types from previous locations including the crime scene. A lack of chronological layering of the retained sediments was observed indicating that techniques that can identify the components of mixed provenance samples are important for analysing footwear sediment samples. It was also identified that the type of footwear appeared to have an influence on what particles were retained, with high relief soles that incorporate recessed areas being more likely to retain sediments transferred from 'older' locations from the journey history. In addition, the inners of footwear were found to retain sediments from multiple locations from the journey history that are less susceptible to differential loss in comparison to the outer sole. These findings provide important data that can form the basis for the effective collection, analysis and interpretation of sediments recovered from both the outer soles and inners of footwear, building on the findings of previously published studies. These data offer insights that enable inferences to be made about mixed source sediments that are identified on footwear in casework, and provide the beginnings of an empirical basis for assessing the significance of such sediment particles for a specific forensic reconstruction.

An experimental study addressing the use of geoforensic analysis for the exploitation of improvised explosive devices (IEDs).

The use of geoforensic analysis in criminal investigations is continuing to develop, with the diversification of analytical techniques, many of which are semi-automated, facilitating prompt analysis of large sample sets at a relatively low cost. Whilst micro-scale geoforensic analysis has been shown to assist criminal investigations including homicide (Concheri et al., 2011 [1]), wildlife crime (Morgan et al., 2006 [2]), illicit drug distribution (Stanley, 1992 [3]), and burglary (Mildenhall, 2006 [4]), its application to the pressing international security threat posed by Improvised Explosive Devices (IEDs) is yet to be considered. This experimental study simulated an IED supply chain from the sourcing of raw materials through to device emplacement. Mineralogy, quartz grain surface texture analysis (QGSTA) and particle size analysis (PSA) were used to assess whether environmental materials were transferred and subsequently persisted on the different components of three pressure plate IEDs. The research also addressed whether these samples were comprised of material from single or multiple geographical provenances that represented supply chain activity nodes. The simulation demonstrated that material derived from multiple activity nodes, was transferred and persisted on device components. The results from the mineralogy and QGSTA illustrated the value these techniques offer for the analysis of mixed provenance samples. The results from the PSA, which produces a bulk signature of the sample, failed to distinguish multiple provenances. The study also considered how the environmental material recovered could be used to generate information regarding the geographical locations the device had been in contact with, in an intelligence style investigation, and demonstrated that geoforensic analysis has the potential to be of value to international counter-IED efforts. It is a tool that may be used to prevent the distribution of large quantities of devices, by aiding the identification of the geographical location of key activity nodes.