Fingerprint forgery has been becoming easier when the available materials can be used to produce fingermarks onto any matrix of interest. However, there are relatively rare cases about fingerprint forgery though sparse reports were mentioned it even at the start of 20th century, resulting in few practical recognition methods for law enforcement practice to identify forged fingerprints presently. Nevertheless, the lack of corresponding examination methods would cause embarrassment for fingerprint detection as the increasing numbers of cases are recently looming about forged fingerprints or claimed fingerprint forgeries. Therefore, this article tries to focus on the issue of forged fingerprint recognition, beginning with illustrating the relevant research background and successively summarizing the classification of forged fingerprints according to two different criteria, i.e., whether the forgery techniques require the donor’s cooperation or not and the print is visible. The following review is emphatically placed on the research advances of technologies about forged fingerprint recognition that mainly involves with morphological comparison approaches and machine learning convolution (especially deep learning). Finally, a brief analysis is given on the future developing trend of forged fingerprint recognition technology based on the previous expatiation.

Latent fingerprint, one of the most important evidential traces at crime scenes, has always been being a powerful tool for worldwide law-enforcing departments to fight against relevant crimes and authenticate personal identity. In the past two decades, the deep integration of traditional fingerprint development with nanotechnology, immunofluorescence, biological aptamer and other emerging technologies has provided possibilities for evidential fingerprint to have its harbored chemical and biological information recognized. Electrochemical detection has shown unique advantages for analysis of material and component thanks to its high sensitivity, available controllability, low cost and convenient coalescence with other instruments. Consequently, forensic scientists have increasingly paid more attentions to the application of electrochemical detection into latent fingerprint development in recent years. Here, the research progress home and abroad was comprehensively reviewed about latent fingerprint development with negative image exposed through electrochemical deposition, electrogenerated chemiluminescence and surface plasmon spectroscopy, having placed the emphasis on the application status and prospect of electrochemical detection for latent fingerprint to be able to nondestructively detect on-site and relevant leftovers to analyze.

Objective To analyze the differences between the characteristics of imprints from bionic silicone fingerprint membrane and those of real fingerprints. Methods The bionic silicone fingerprint memrance was made with fine-pore silica gel, having it imprinted on A4 paper and smooth ceramic tile under the respective mild, medium and heavy pressure. Such the imprints from above handling were scanned and recorded with Epson scanner at 1200dpi, 2400dpi and 3200dpi, having them compared with their characteristics against those of real fingerprint. Results There were no influences of pressure magnitude on the characteristics of edge lines and “artificial marks” of imprints from bionic fingerprint membrane. The bionic fingerprint membranes exposed their imprints into more marks of “Exposed White”, “Broken” and “Raised”, rendering the “dot” marks around the small furrow, emerging the “halo dye” marks surrounding their fingerprint lines, and coming forth the changed locations and shapes of “Sweat Pore” marks. However, the real fingerprints were natural and more coherent lines, leaving the sweat pore marks having their location and shape almost unchanged. Conclusion The differences between the imprint from bionic fingerprint membrane and the real fingerprint can be reflected from their characteristics of lines, mainly demonstrated with “Exposed White”, edge marks, number of sweat pores, human handling signs and the others alike.

Objective To prepare β-CD@AuNPs for exploration about visual exposure of sweat latent fingerprints which to have their contained lactic acid bound into the preparation. Methods β-CD@AuNPs was prepared through reduction of HS-β-cyclodextrin (HS-β-CD) under microwave heating. Lactic acid, one content-higher component of sweat, was bound into β-CD@AuNPs by way of inherent coalescence between them, resulting in the latent sweat fingerprints having turned out a different color of β-CD@AuNPs solution from that of either the blank or other alternative substance. HSV data processing software was adopted to handle the unveiling color so that the revealed sweat latent fingerprints were more vivid to be visually detected through their contained lactic acid. Results A quantitative relationship was present between the changing color of β-CD@AuNPs and the amount of lactic acid, demonstrating the ability of β-CD@AuNPs to distinguish fresh latent sweat fingerprints from the old ones. Conclusions β-CD@AuNPs had been innovatively utilized to detect lactic acid in sweat latent fingerprints, eligible for making the obtained results successively processed into HSV data for quantification. Sweat latent fingerprints can be realized into synchronous retrieval of their visual two-dimensional patterns and composition information.

Objective To explore the influence of metabolizing human fingers’ ventral epidermis on size of the sweat pore indicating tertiary characteristics of fingerprint, with focusing on the regularity and stability of the changing size of sweat pore during epidermal replacement. Methods Each ten young subjects of both men and women, aging between 18 and 22, were selected to pick up 300 sampling fingerprints from their index fingers being inked once every two days within a 30-day epidermal replacement period. The samples were photographed, marked and measured with a magnification-high digital microscope, rendering the changing size of same one sweat pore to be analyzed. Results The male subjects varied of their average sweat pore’s size from 29.5~116.5μm while the female ones were from 29.5~93.5μm. The maximal and minimal sizes of same sweat pore were 80.5μm and 68.5μm for males, contrasting to the females’ 58.5μm and 45μm. Conclusions Male fingerprint-housing sweat pore is generally larger in size than that of female’s. Dynamic changing occurs to the size of sweat pore along with the epidermal replacement, appearing individual-dependent variation range that also reveals greater for male than female. The discovery that sweat pores’ sizes vary from 29.5~116.5μm puts an expectation to ponder the conclusion from previous relevant literatures/researchers that little significance was believed for classification into the size of fingerprint-housing sweat pore.

Objective To design the relevant primers and have qPCR adopted for detection of the related diatoms, cyanobacteria and aeromonas (those widely-distributed aquicolous microbes) and verified of the specificity and sensitivity about their forensic applicability into drowning diagnosis. Methods Six pairs of specific primers of UPA, ND, CBR, AER, HLYA and rPOD were designed for detection of drowning-related planktons (the three kinds indicated above). 20 standard strains of plankton were amplified of their DNA to determine the specificity and sensitivity. 38 rabbits (16 ones as the drowned, DG; 16 ones as the postmortem submersion, PSG; and 6 ones as the blank control, BCG) were tested of their tissues of lung, liver and kidney. The overall positive rate of the 6 pairs of primers was calculated through their amplified products and compared with the observation under electron microscopy so as to confirm the effectiveness of the established method for diagnosis of drowning. Results Both ND and UPA had certain diatoms specifically amplified, so had CBR to cyanobacteria, and AER, HLYA, rPOD to aeromonas, respectively. The sensitivity of the 6 pairs of primers was 0.0001ng except for UPA’s 0.001ng with nitzschia. 38 experimental rabbits showed their qPCR results, leaving the 16 drowned ones being positive from all the lungs yet only 13 livers and 14 kidneys (rendering an overall positive rate as 87.50%); the 16 PSG ones being positive from 5 lungs while all their livers and kidneys negative; and the 6 BCG ones being all negative. Electron microscopy exposed that the 16 drowned rabbits were all positive with every lung, liver and/or kidney, being almost consistent with the qPCR results; the 16 PSG ones were positive from just 5 lungs and negative for all livers and kidneys along with the rest of lungs; and all samples of the 6 BCG ones were negative, too. Statistical analysis demonstrated no significance among the detection results of the 38 experimental rabbits between the two methods (the here-established qPCR detection and electron microscopy) (P=0.49>0.05) and neither among the detection results of all the 38 rabbits’ lungs, livers and kidneys (P=0.29>0.05). Conclusions The selected 6 primers are of high sensitivity and specificity for diagnosis of drowning when combined with qPCR detection, revealing good application prospect.

For fire investigation, scene is the origin and the relevant investigation is the core. The key task of fire scene investigation is to find out the bound/site of fire origin, ignition time and fire cause. Based on the interaction between fire and object or human involved, together with their changing with time and space, four key factors were here summarized about fire scenes: fire patterns, evidential materials, involved people and available electronic evidence. Such the key factors were systematically scrutinized into their evolving mechanism with fire development. Focused on the goal of scene investigation, discussions were deliberated about the utilization of the uncovered evolving mechanism into reverse deduction so that the assistance could be offered for analysis of the bound/site of fire origin, ignition time and fire cause, aiming to provide a reference for fire investigators to carry out fire scene investigation more scientifically and accurately.

Objective To scrutinize the traces left on the pin-vane mortised locks undergone with soft and hard unlocking tools so as to provide a reference for identification of such a new technical unlocking. Methods Three different brands of pin-vane mortised locks were marked into 3 groups (A, B, C), with each group having 10 locks among which one piece was left intact as the blank sample for its group and the other nine ones were operated with keys to imitate locking and unlocking. Among the nine locks operated, one was handled with its genuine key as the control sample for normal using and the rest 8 ones were technically opened with the soft and hard unlocking tools. Every one of the locks mentioned above was individually observed under microscope. Results Morphological changes were observed directly on the appearance of some tested locks, revealing deformation of the keyholes, residua left on the cylinder plugs, broken marks on the cylinder and the other abnormal signs. Traces on the key slot were among the most stabilized characteristics. Some of the round-head and/or flat-end pins were exposed of cutting marks, deformation or even fractures, with the relevant pin holes appearing morphological changes, too. Marks were also found on sliding blocks and columns, with the latter even likely bending when they were really a blade. In the C group, marks caused from steel balls appeared much more obvious inside the cylinder of tested locks than those of the normal-using lock. Conclusions The traces left with soft and hard unlocking tools have been here demonstrated of their positions, patterns and interspersion on the pin-vane mortised locks, with the main points of such kind of examination being concluded. Whether a pin-vane mortised lock has been opened with one soft and hard unlocking tool could get reference from this survey.

Objective To establish a gas chromatography-mass spectrometry (GC-MS) method combining with headspace solid-phase microextraction (HS-SPME) for simultaneous determination of sevoflurane and its metabolite hexafluoroisopropanol (HFIP) in blood and urine. Methods Sampling blood or urine (1.0mL) was added into a 10mL headspace vial, and followed to mix with 1.0mL deionized water and 1.0g NaCl, finally having the vial sealed. The headspace gas was extracted with a SPME fiber (50/30μm DVB/CAR-PDMS) at 50ºC for 20 minutes and successively analyzed into GC-MS (under EI condition) through an HP-PLOT/Q (30m×0.32mm×20μm) capillary column, with the data being acquired under FULL SCAN mode. Results Both sevoflurane and HFIP showed good linear relationship between peak area and concentration within the investigated concentration ranges, with their coefficients of determination being R²≥0.996, their limit of detection (LOD) and limit of quantitation (LOQ) as respective of 1.5μg/L and 5.0μg/L in biological specimens, their average recoveries among 95%-103% and RSD≤4.3% (n=5). Conclusions The here-developed HS-SPME/GC-MS method is of high speed, simplicity, efficiency, good enrichment and low interference for simultaneous determination of sevoflurane and its metabolite HFIP in blood and urine.

Objective To explore the feasibility of identifying the writings with their componential identity from thermosensitive erasable signing pens using microscopic attenuated total internal reflectional Fourier transform infrared spectroscopy (ATR-FTIR). Methods With a collection of 49 kinds of thermosensitive erasable signing pens (from color- and batch-different products of 5 various brands) and 5 brand-discrepant common signing pens, the writings were tested from the collected pens via microscopic ATR-FTIR. At the same time, the influence of paper was investigated on the infrared spectrum of writing. Results All the 49 erasable writing samples had one strong infrared absorption peak near the respective 2916, 2850, 1729, 1513, 1455, 1254, 1214, 1170, 830, 739 and 698cm-1, revealing that those brand-different yet color-same erasable pens were shown of their writings into the peaks of obvious difference at both position and intensity. For those model-same yet color-different pens, their writing samples were also found of obvious difference with their infrared absorption peak and intensity. Conclusions The microscopic ATR-FTIR can identify not only whether one suspicious writing has been forged about its componential identity but also the brand of erasable pen used for forging. This method is of fast, lossless and accurate advantages, capable of providing effective means for the inspection of forged documents.

For cognitive forensics, contextual bias is used to describe an inclination that the results of a forensic analysis are influenced from task-irrelevant background information. Over the past twenty years, such correlative events occurred and/or were reported with erroneous identifications (e.g., Brandon Mayfield Case in 2004), theoretical and empirical researches (e.g., one of the best known forensic bias research papers by Dror, Peron and Charlton in 2006) and official notices (e.g., The U.S. National Research Council report on forensic science in 2009), demonstrating that contextual bias can influence decision making in forensic science, especially in empirical and subjective disciplines based on visual pattern recognition (among them are perhaps the inclusions of traditional examinations of fingerprint, handwriting, toolmark and others alike). Several recent publications suggest that contextual bias can even affect objective and quantitative instrument-based disciplines, mentioning about DNA typing, forensic toxicology. Here, an introduction was firstly carried out into the contextual bias about its conception and history of cognitive forensics, followed to respectively illustrate the effect of contextual bias on screening test, confirmatory analysis and result interpretation in forensic toxicology practice. Moreover, discussions were made with the current disagreements on whether examinators should be exposed to contextual information, having summarized three points against access to task-irrelevant background information: role’s confusion of forensic scientist, illusional reasoning and subconscious cognitive bias. Finally, six measures were proposed about bias controlling from information management procedure, cognitive education and training, blind verification, detailed document to updating technique. There is a big expectation about cognitive forensics in China, demanding launching active cooperations between forensic scientists and cognitive psychologists to investigate cognitive factors in forensic science practice.

Forensic science standard system is not only a norm and tool for the whole of all related standards to put into research and management but can provide scientific guidance for any standard to develop, revise and apply, for standard resource database to construct on relevant classification relations, for each specialty to build up contextual relationships of standardized objects and their elements, and overall promote forensic science to develop on the way of standardization and normalization. In China, a suitable work mode may at present require top-level design to establish a standard system and improve standards into systematization and coordination in order for forensic science to better develop and progress, thus rendering the conduciveness to efficiency enhancement, especially for standardized objects to select and reasonably divide, for standards to simplify, integrate and mitigate cross duplication. An international comparison was here made on the construction of standard system that is respectively adopted with Europe, United States, Canada and Australia. Analysis was therewith carried out into Sino-overseas standard systems about their institutional foundation and practical requirements, highlighting the similarities and differences in manifestation, classification dimension, classification management, systematic concept, function and application, and pointing out foreign countries’ good experiences and ways, e.g., adhering to orientation at practice and demand, enriching the genres of standardized documents, emphasizing general standards and quality management regulations, paying attention to coordination and tracking management, enhancing the timeliness of standards, optimizing supportive working mechanism. This essay is purported to provide beneficial reference for forensic science standard system to improve construction in China.

Driven by big data and visualization technologies, knowledge graph has been rapidly developed about its theory and methods in recent years, therewith having provided a new way to understand the realm of knowledge. The knowledge graph can directly reveal the characteristics and principles of scientific activities. Here, VOSviewer, a tool for knowledge graph to map and parse, was adopted to analyze the large quantity of literatures relating to trace evidence from Web of Science. The results were derived from the main countries, institutions and authors who had contributed more publications about trace evidence worldwide. Meanwhile, there was a manifest of both the characteristics and evolution trend of keywords about trace evidence in different periods. Consequently, this survey brought forth a quick way to know the institutions/countries and authors who had published more articles of researches about trace evidence, together with a comprehension being learnt into their partnership and cooperation. Besides, such a survey can help grasp the research hotspots and developing trends of trace evidence. Certainly, an informative reference could be also provided for communication and learning among relevant peers in the field of trace evidence through a survey of the kind.

Synthetic cannabinoids (SCs), also known as new psychoactive substances (NPS), are synthetic potent agonists targeting to endogenous cannabinoid CB1 and CB2 receptors. SCs’ intake will lead to symptoms like marijuana toxicity reaction, thereby posing a major threat to public health. China is globally the first to fully regulate SCs, having implemented the relevant statutes on July 1, 2021. Agonists of SC’s receptors have a complex molecular structure, consisting of four components termed as ‘head’ ‘tail’ ‘core’ and ‘linker’. Such a structural complexity offers many opportunities for chemical structural transformation to evade drug control and legislation. Moreover, its ever-emerging varieties and rapid variation have even been bringing forth diverse designations about the related SCs in domestic or international literature. Still, there has till now been a lack of introduction on the rules to designate SCs. Drug controlling labs often encounter the situation of different compounds with same name or different names with same compound in case investigations, leaving troubles to drug control work. At present, there are four main ways for designating SCs: colloquial, serial, systematically chemical and systematically abbreviated, with the last systematically abbreviated being by far the most common choice. The systematically abbreviated way takes from the structure of 4 parts of SCs, combining in the order of “linked functional group-tail-core-linker” so that it can more systematically describe some structurally similar substances and easily identify the newly discovered SC’s structure. However, due to the lack of uniform and comprehensive regulations and introduction of rules about designating SC’s systematically abbreviated names, a variety of different abbreviated names have appeared for one SC substance, therewith further complicating the designation system. This paper reviews the structural classification and four designation systems of SC, together with the prospect for SC’s nomenclature system and introduction of some international retrieval database of NPS, purposing to strengthen the understanding of molecular structure, modification rules and designating methods of SC substances, meanwhile improve the accuracy and effectiveness in case investigation, judicial adjudication and academic research. Besides, Attention must be continuously paid to the structure of parent nucleus beyond the regulatory scope of SCs because such a possibility cannot be ruled out that the parent nucleus would mutate into new series of SCs in the future. In conclusion, the nomenclature of SCs really needs to unify and the relevant pharmacological and toxicological data of suspicious structures require to further refine so as to both ensure correct and effective communication and avoid omissions between industry researchers and law enforcement regulators.

Vehicle collision cases frequently occur, even having involved with casualties, huge social impact, complicate scenes and excessive apposite items of crime so that difficulties are often met in crime scene reconstruction and definition of criminal behaviors. On the perspective of crime constituents, vehicle collision cases should be placed of their core points of investigation and analysis on the subjective states of drivers related. However, the subjective state of a criminal suspect is an invisible and intangible psychological reality hidden with the suspect. In order to effectively analyze and judge the subjective state of a crime-relating driver, an appropriate method is necessary to construct about inferring such a driver’s subjective psychological reality based on the objective manifestation of the involved vehicle collision case. An elucidation was here emphatically introduced into the key points of on-site investigation through inferring the crime-comitting drivers’ subjective states based on the objective manifestation of vehicle collision cases.

Objective With statistical analysis into DNA matching from the involved 4454 theft cases through National DNA Database of Public Security, the potential relationship is to ascertain for a reference to provide about improving the applicability of evidential DNA in detecting theft cases. Methods 4454 theft cases, out from 95934 pieces occurring during 2014 to 2018, were selected with their respective related DNA being matched against the one in National DNA Database of Public Security. The relevant data were inquired in the systems of both the relating DNA laboratory’s verification-analysis and the scene inspection-investigation information. Six indicators were of statistical analysis to set up in accordance with the committing-crime means and durations, types of biological sample, main sites of extraction, ratios of DNA matched into database, and main sites of extraction linking to different committing-crime means. The main extracting sites where to get DNA matching easier were underlined from the selected theft cases. Results From the large number of main extracting sites enumerated of quantity-more DNA matching with the 4454 cases, a gross DNA matching rate of 4.64% was achieved under the 40.49% scene evidential data which were entered into the database and thereby demonstrated a 11.46% successful matching from the inputted data. Conclusions The key extracting sites are different about their getting DNA matching easier for theft cases according to the committing-crime means. It is crucial to efficiently improve the evidential DNA into solving theft cases whether scene investigators can find and extract those biological materials of higher rate for both DNA testing and matching.

Though the strengthening of national controlling about gun has turned gun-related cases into a downward trend year by year, deaths are still encountered from informal gun’s shooting for forensic investigation at times. Usually, the guns involved with related cases are characteristic of simple structure, poor airtightness, lack of rifling on their bores and shape-irregular bullets adopted, therewith having mostly resulted in blind track wounds, difficulty to find the warheads and shells at the scene. In pursuit to provide reference for public security and/or judicial professionals to handle such cases, this essay made a comparative analysis with four cases relating to informal guns’ shooting investigated by us in recent years, having focused on the characteristics of the firearms used and injuries caused, summarized the key points on scene investigation and corpse examination, and finally analyzed the occurring causations and countermeasures about the cases.