Forensic Exchange Analysis of Contact Artifacts on Data Hiding Timestamps

When computer systems are increasingly important for our daily activities, cybercrime has created challenges for the criminal justice system. Data can be hidden in ADS (Alternate Data Stream) without hindering performance. This feature has been exploited by malware authors, criminals, terrorists, and intelligence agents to erase, tamper, or conceal secrets. However, ADS problems are much ignored in digital forensics. Rare researches illustrated the contact artifacts of ADS timestamps. This paper performs a sequence of experiments from an inherited variety and provides an in-depth overview of timestamp transfer on data hiding operations. It utilizes files or folders as original media and uses the timestamp rules as an investigative approach for the forensic exchange analysis of file sets. This paper also explores timestamp rules using case examples, which allow practical applications of crime scene reconstruction to real-world contexts. The experiment results demonstrate the effectiveness of temporal attributes, help digital forensic practitioners to uncover hidden relations, and trace the contact artifacts among crime scenes, victims, and suspects/criminals.

Self-similar turbulent vortex rings: interaction of propellant gases with blood backspatter and the transport of gunshot residue

Self-similar turbulent vortex rings are investigated theoretically in the framework of the semi-empirical turbulence theory for the modified Helmholtz equation. The velocity and vorticity fields are established, as well as the transport of passive admixture by turbulent vortex rings. Turbulent vortex rings of propellant gases originating from the muzzle of a gun after a gunshot are an important phenomenon to consider in crime scene reconstruction. In this work, it is shown that this has a significant repercussion on the outcome of backward blood spatter resulting from a gunshot. Turbulent vortex rings of propellant gases skew the distribution of bloodstains on the ground and can either propel blood droplets further from the target, or even turn them backwards towards the target. This is revealed through the final bloodstain locations and the respective distributions of the number of stains and their area as a function of distance from the target for two different shooter-to-target distances. An image of the propagating muzzle gases after bullet ejection is overlaid with the predicted flow field, which reveals satisfactory agreement. Gunshot residue is an important factor in determining the events of a violent crime due to a gunshot and are considered to be entrained and transported by the propellant gases. The self-similar solutions for the flow, vorticity and concentration of gunpowder particles are predicted and the results are shown to be within the measured range of a limited set of experimental data.

Latent Fingerprint Visualization and Subsequent DNA Extraction Using Electron Beam Evaporation of Metallic Ultra-Thin Films

Background: Proper detection and subsequent extraction of biological evidence are crucial for crime scene reconstruction. Vacuum metal deposition is currently an effective technique used in latent fingerprint development. However, the established procedures commonly undergo a direct plasma bombardment, a high ablation fluence and/or a high temperature process in vacuum metal deposition system. Method: In this work, electron beam evaporation (EBE) was used to investigate the development of latent fingerprints and subsequent DNA extraction of biological evidence. Gold or copper is preferentially nucleated on the background surfaces rather than the fingerprint residues due to the difference of the nature of the surface, which indicates that the gold / copper and copper agglomerates are binding to the fingerprint valleys not the ridges of the fingerprint, revealing bright patterns with excellent ridge detail clarity on black surfaces. Result: It is demonstrated that the co-extraction of the latent fingerprints and DNA is attributed to electron beam evaporated one-step process with relatively low energy bombarding energetic species and neutral particles, less possibility of contamination and without toxic and fluorine-based gases. Conclusion: Our results demonstrate that EBE is a promising technique for the latent fingerprints and DNA co-extraction.

Insect succession pattern on decomposing pig carcasses in Tasmania: a summer study'

Insect succession has been studied around the world using the predictable and mostly sequential arrival pattern of different insect species that are attracted to a decomposing carcass. In cases of suspicious death of humans and animals, carrion insects may be used to assist in crime scene reconstruction. The present research represents the first study in forensic entomology to be undertaken in Tasmania, investigating insect succession patterns on decomposing pig carcasses and providing a preliminary database of forensically important insects. Six pig carcasses were placed in two contrasting locations (rural and urban) in northern Tasmania. Insect successional waves were recorded over a 40-day study during the austral summer season. Results showed that decomposition rates and insect assemblages varied between each location. Eleven insect taxa, representing nine families, were identified in association with the decomposition of the pig carcasses at both localities. Blowflies present on the pig carcasses throughout the decomposition process were Calliphora stygia Malloch (Diptera: Calliphoridae) at both sites and Lucilia sericata (Meigen) at the urban site only. These preliminary results will provide useful information in any future casework involving human remains and associated insect material in Tasmania.