The Effect of Time and Temperature on the Persistence and Quality of Latent Fingerprints Recovered from 60-Watt Incandescent Light Bulbs

To understand how time and temperature could affect latent fingerprints, wooden pallets were used to construct five units that each housed ten 60-watt incandescent light bulbs. Fingerprints were deposited on the top, middle, and base of the globes. The bulbs were powered on (except the control bulb in each unit) for 18, 48, 72, 120, 168, 336, 504, and 672 h. Fingerprints recovered from the bulbs by tape lift after black powder processing were given a quality score. A thermal imaging camera determined temperatures on three areas of the bulbs. Fingerprints on the top of the globe (156.3°C) had the lowest quality score, and fingerprints on the middle of the globe (112.6°C) had the highest quality score. The mean quality scores of the three temperature classes were within one standard deviation of one another, meaning there is no way to estimate fingerprint age based on its quality after heat exposure.     

A forensic examination of four popular cross‐platform file‐sharing apps with Wi‐Fi P2P

File‐sharing apps with Wi‐Fi hotspot or Wi‐Fi Direct functions become more popular. They can work on multiple platforms and allow users to transfer files in a concealed manner. However, when criminals use these apps in illegal activities, it becomes an important issue for investigators to find digital evidence on multiple platforms. At present, there are few studies on this topic, and most of them are limited to the single platform problem. In this paper, we propose a forensic examination method for four popular cross‐platform file‐sharing apps with Wi‐Fi hotspot and Wi‐Fi Direct functions: Zapya, SHAREit, Xender, and Feem. We use 22 static and live forensic tools for 11 platforms to acquire, analyze, and classify the forensic artifacts. In our experiments, we find many useful forensic artifacts and classify them into six categories. The experimental results can support law enforcement investigations of digital evidence and provide information for future studies on other cross‐platform file‐sharing apps.     

普通数码相机光谱成像技术在文件检验中的应用研究

根据光谱成像技术原理,论述了用普通数码相机实现光谱成像的方法与特点,并从定性角度介绍了普通数码相机光谱成像技术在文件检验中的主要应用.     

A Novel Application of Infrared Imaging for the Diagnosis of Death by Fire

This paper demonstrates a novel and simple technique for the diagnosis of death by fire using a digital infrared (IR) camera system. At autopsy, the inhalation of soot by a fire victim is a definite indicator proving a vital reaction during the fire. However, there can be difficulties in confirming the presence of soot because of the relative lack of soot or the similarity in color between soot and surrounding tissues. To evaluate the effectiveness of IR imaging at autopsy, we acquired internal images of the respiratory and gastrointestinal system by both an ordinary color and IR cameras. Using our method, the inhaled soot is visible as black particles or deposits, while the blood is transparent and the surrounding tissue is whitened. This technique enables the detection of normally undiscriminating soot in an ordinary color image. This is the first report suggesting the usefulness of IR imaging in forensic autopsy for the diagnosis of death by fire.     

Identifying Diagonal Cutter Marks on Thin Wires Using 3D Imaging

We present work on matching 2‐mm‐thick wires using optical 3D imaging methods. Marks on such small surfaces are difficult to match using a comparison microscope as this 2D imaging method does not provide height data about the sample surface. Moreover, these 2D microscopy images may be affected by illumination. Hence, the reference and investigated sample should be present at the same time. We employed scanning white light interferometry and confocal microscopy to provide quantitative 3D profiles for reliable comparison of samples that are unavailable for simultaneous analysis. We show that 3D profiling offers a solution by allowing illumination‐independent sample comparison. We correctly identified 74 of 80 profiles using consecutive matching striae (CMS) criteria, and we were able to match samples based on profiles measured using different 3D imaging devices. The results suggest that the used methods allow matching cutter marks on thin wires, which has been difficult previously.     

体视学技术在医学影像学中的应用及其法医学价值

基于Cavalieri原理的体视学技术经常运用在组织学和病理学的研究中,但是现在,这种技术已经被运用于医学影像学(如CT、MRI、ECT、超声等)的测量。体视学的方法提供了一个非侵入性的、精确的、无偏的、简单的和快速的测量方法。所以该方法在医学影像学的形态计量学的测量中有临床使用价值。而影像资料的定量测量结果则有助于法医学实践。     

Characterization of Digital Cameras for Reflected Ultraviolet Photography; Implications for Qualitative and Quantitative Image Analysis During Forensic Examination

Reflected ultraviolet imaging techniques allow for the visualization of evidence normally outside the human visible spectrum. Specialized digital cameras possessing extended sensitivity can be used for recording reflected ultraviolet radiation. Currently, there is a lack of standardized methods for ultraviolet image recording and processing using digital cameras, potentially limiting the implementation and interpretation. A methodology is presented for processing ultraviolet images based on linear responses and the sensitivity of the respective color channels. The methodology is applied to a FujiS3 UVIR camera, and a modified Nikon D70s camera, to reconstruct their respective spectral sensitivity curves between 320 and 400 nm. This method results in images with low noise and high contrast, suitable for qualitative and/or quantitative analysis. The application of this methodology is demonstrated in the recording of latent fingerprints.     

Optimizing Ballistic Imaging Operations

Ballistic imaging systems can help solve crimes by comparing images of cartridge cases, which are recovered from a crime scene or test‐fired from a gun, to a database of images obtained from past crime scenes. Many U.S. municipalities lack the resources to process all of their cartridge cases. Using data from Stockton, CA, we analyze two problems: how to allocate limited capacity to maximize the number of cartridge cases that generate at least one hit, and how to prioritize the cartridge cases that are processed to maximize the usefulness (i.e., obtained before the corresponding criminal case is closed) of hits. The number of hits can be significantly increased by prioritizing crime scene evidence over test‐fires, and by ranking calibers by their hit probability and processing only the higher ranking calibers. We also estimate that last‐come first‐served increases the proportion of hits that are useful by only 0.05 relative to first‐come first‐served.     

Investigation of the variability in the tool marks produced by modified blank firing pistols on fired 7.65 mm projectiles

Firearms identification has an important place in forensic ballistic investigations since the weapons are widely used in criminal offences. Firearm examiners resolve many case files, through the use of automatic systems or comparison microscopes. Advanced forensic technologies like BALİSTİKA helps to record and analyze non standard ballistic evidence. In today's world, with the ease of access to materials and production technique information, pistols modified from blank firers are frequently encountered as crime tools. In this study, the characteristics of 7.65 mm fired cartridge cases obtained by controlled shots from blank firing modified pistols were examined, and their detection performances were compared by means of the Balistika system. Although distinctive differences are not expected after successive test shootings, balistically important changes were seen after the use of blank firing modified pistols and the 3D imaging system proved to be useful in observing such differences. The analyses showed that the modifications in weapons lead to variation in the ballistic characteristics and reduce the accuracy of the detection performance, which may result in flawed forensic decisions. It was also found that the deviations in ballistic impressions of modified blank firing pistols were greater than that of standard fabricated and hand-made pistols. This unique study contributed to the forensic sciences literature by focusing on the impact of modified weapons on ballistic characteristics.     

Preliminary Observations on the Ability of Hyperspectral Imaging to Provide Detection and Visualization of Bloodstain Patterns on Black Fabrics

Abstract: The analysis of bloodstain patterns can assist investigators in understanding the circumstances surrounding a violent crime. Bloodstains are routinely subjected to pattern analysis, which is inherently dependent upon the ability of the examiner to locate and visualize bloodstain patterns on items of evidence. Often, the ability to properly visualize bloodstain patterns is challenging, especially when the stain patterns occur on dark and/or patterned substrates. In this study, preliminary research was performed to better understand how near‐infrared reflectance hyperspectral imaging (HSI) could be used to observe bloodstain patterns on commonly encountered black fabrics. The ability of HSI to visualize latent bloodstains on several commonly encountered substrates is demonstrated. The images acquired through HSI are of sufficient quality to allow for differentiation between stains produced from an impact mechanism or a transfer mechanism. This study also serves as a proof of concept in the differentiation of multiple staining materials. Because of its ability to generate spectral data, the data provide a preliminary separation of stains where more than one type of stain existed.