A comparison of the ability of experts and non-experts to differentiate between adult and child human bite marks using receiver operating characteristic (ROC) analysis

Fifty colour prints of human bite marks were sent to 109 observers who were asked to decide using a six point rating scale, whether the marks had been produced by the teeth of an adult or a child. The observers consisted of accredited senior forensic dentists, accredited junior forensic dentists, general dental practitioners, final year dental students, police officers and social workers. The results were compared against a “gold standard” which was the actual verdict from the case. Comparison of the results between the groups of observers and the standard was made using Receiver Operating Characteristics (ROC) methodology. The best decisions were made by senior/junior experts or final year dental students. General dental practitioners and police officers were least able to differentiate correctly between adult and child bite marks. The effect of training is important and its effects need to be assessed in more detail in future studies.     

Shoeprint image retrieval and crime scene shoeprint image linking by using convolutional neural network and normalized cross correlation

A shoeprint image retrieval process aims to identify and match images of shoeprints found at crime scenes with shoeprint images from a known reference database. It is a challenging problem in the forensic discipline of footwear analysis because a shoeprint found at the crime scene is often imperfect. Recovered shoeprints may be partial, distorted, left on surfaces that do not mark easily, or perhaps come from shoes that do not transfer marks easily. In this study, we present a shoeprint retrieval method by using a convolutional neural network (CNN) and normalized cross-correlation (NCC). A pre-trained CNN was used to extract features from the pre-processed shoeprint images. We then employed NCC to compute a similarity score based on the extracted image features. We achieved a retrieval accuracy of 82% in our experiments, where a “successful” retrieval means that the ground truth image was returned in the top 1% of returned images. We also extend our shoeprint retrieval method to the problem of linking shoeprints recovered from crime scenes. This new method can provide a linkage between two crime scenes if the two recovered shoeprints originated from the same shoe. This new method achieved a retrieval accuracy of 88.99% in the top 20% of returned images.     

The evaluation of methods for soil analysis under simulated scenes of crime conditions

Five simulated scenes of crime have been studied in which the soils adhering to shoes, car tyres and plant roots have been compared with multiple control samples using dry colour, ashed colour, pH, saccharide levels and particle size analysis. Colour and pH were found to be as reproducible under simulated scenes of crime conditions as for true duplicates from homogeneous soil, whereas the variation in saccharide levels was slightly greater than for true duplicates. The interpretational scheme developed for the silt and sand fractions of homogeneous soils was applied to the samples from each simulated scene of crime and every comparison was found to be similar at the 99% confidence limit.     

Decision support for using mobile Rapid DNA analysis at the crime scene

Mobile Rapid DNA technology is close to being incorporated into crime scene investigations, with the potential to identify a perpetrator within hours. However, the use of these techniques entails the risk of losing the sample and potential evidence, because the device not only consumes the inserted sample, it is also is less sensitive than traditional technologies used in forensic laboratories. Scene of Crime Officers (SoCOs) therefore will face a ‘time/success rate trade-off’ issue when making a decision to apply this technology.In this study we designed and experimentally tested a Decision Support System (DSS) for the use of Rapid DNA technologies based on Rational Decision Theory (RDT). In a vignette study, where SoCOs had to decide on the use of a Rapid DNA analysis device, participating SoCOs were assigned to either the control group (making decisions under standard conditions), the Success Rate (SR) group (making decisions with additional information on DNA success rates of traces), or the DSS group (making decisions supported by introduction to RDT, including information on DNA success rates of traces).This study provides positive evidence that a systematic approach for decision-making on using Rapid DNA analysis assists SoCOs in the decision to use the rapid device. The results demonstrated that participants using a DSS made different and more transparent decisions on the use of Rapid DNA analysis when different case characteristics were explicitly considered. In the DSS group the decision to apply Rapid DNA analysis was influenced by the factors “time pressure” and “trace characteristics” like DNA success rates. In the SR group, the decisions depended solely on the trace characteristics and in the control group the decisions did not show any systematic differences on crime type or trace characteristic.Guiding complex decisions on the use of Rapid DNA analyses with a DSS could be an important step towards the use of these devices at the crime scene.     

Real-time forensic DNA analysis at a crime scene using a portable microchip analyzer

An integrated lab-on-a-chip system has been developed and successfully utilized for real-time forensic short tandem repeat (STR) analysis. The microdevice comprises a 160-nL polymerase chain reaction reactor with an on-chip heater and a temperature sensor for thermal cycling, microvalves for fluidic manipulation, a co-injector for sizing standard injection, and a 7-cm-long separation channel for capillary electrophoretic analysis. A 9-plex autosomal STR typing system consisting of amelogenin and eight combined DNA index system (CODIS) core STR loci has been constructed and optimized for this real-time human identification study. Reproducible STR profiles of control DNA samples are obtained in 2 h and 30 min with ≤0.8 bp allele typing accuracy. The minimal amount of DNA required for a complete DNA profile is 100 copies. To critically evaluate the capabilities of our portable microsystem as well as its compatibility with crime scene investigation processes, real-time STR analyses were carried out at a mock crime scene prepared by the Palm Beach County Sheriff's Office (PBSO). Blood stain sample collection, DNA extraction, and STR analyses on the portable microsystem were conducted in the field, and a successful “mock” CODIS hit was generated on the suspect's sample within 6 h. This demonstration of on-site STR analysis establishes the feasibility of real-time DNA typing to identify the contributor of probative biological evidence at a crime scene and for real-time human identification.     

Semen analysis using methods of molecular genetics--a case report

The presented case report describes the exclusion of the suspect of a sexual offence by means of methods of molecular genetics. Pretests for prostate-specific antigen performed at the beginning of the investigation and cytological sperm tests were negative. Nevertheless, by combining the methods of differential lysis and DNA quantification a small number of spermatozoa could be demonstrated in the trace evidence. Subsequently, the profile of the woman's boyfriend, with whom she had had unprotected vaginal intercourse two days before the incident, could be detected in the fraction of the hard lysis.     

Inference structures for crime analysis and intelligence: the example of burglary using forensic science data

There has been much work dedicated to crime analysis and intelligence in recent times. Independently, physical evidence has shown great potential for linking crimes and bringing solid informative data through the increased use of multiple databases. However, their informative potential is still often underestimated and has been poorly integrated into police information systems. We propose a framework that fully introduces this data into an intelligence based system. This framework is built on the study of inference structures extracted from investigators’ every day implicit reasoning processes. Five specific inferences are studied with the particular problem of serial burglary investigation across independent police and legal structures. On the basis of such an analytical approach, a computer prototype has been designed; it has shown great promise and has resulted in several operational successes.     

Latency problems with smothering using soft cover

Smothering by covering the respiratory orifices with soft material is one of the rarely established forms of mechanically induced death by asphyxia. An important reason of latency is that this kind of homicide leaves almost no traces. The two described cases from the autopsy material of the Institute of Legal Medicine in Berlin (CCM) show the limits of medico-legal interpretation and the resulting special responsibility of the investigator. In the first case the defendant denied the offence and was acquitted of the charge, while in the second case the self-confessed offender was convicted.     

Classification of counterfeit coins using multivariate analysis with X-ray diffraction and X-ray fluorescence methods

Counterfeit coins (277 samples) were analyzed by both X-ray diffraction (XRD) and X-ray fluorescence (XRF) methods without any pretreatment. The counterfeit coins were clearly classified into two groups using cluster analysis (CA) and principal component analysis (PCA) for XRD peak patterns. One group (250 samples) was made by a pressed method and another one (27 samples) was made by a nickel-plated method. Using four elements (Cu, Ni, Fe and Zn) and obtaining XRF for 257 samples, they could be divided into four groups by CA. On the other hand, they were classified into five groups using their diameter, thickness, weight, density, density/thickness and density/weight. The latter classification method would suggest something of a change in the process of the pressed method.     

A collaborative approach for incorporating forensic case data into crime investigation using criminal intelligence analysis and visualisation

There is an increasing awareness that the articulation of forensic science and criminal investigation is critical to the resolution of crimes. However, models and methods to support an effective collaboration between the partners are still poorly expressed or even lacking.Three propositions are borrowed from crime intelligence methods in order to bridge this gap: (a) the general intelligence process, (b) the analyses of investigative problems along principal perspectives: entities and their relationships, time and space, quantitative aspects and (c) visualisation methods as a mode of expression of a problem in these dimensions.Indeed, in a collaborative framework, different kinds of visualisations integrating forensic case data can play a central role for supporting decisions. Among them, link-charts are scrutinised for their abilities to structure and ease the analysis of a case by describing how relevant entities are connected. However, designing an informative chart that does not bias the reasoning process is not straightforward. Using visualisation as a catalyser for a collaborative approach integrating forensic data thus calls for better specifications.     

Comparative analysis of synthetic polymers using combinations of three analytical methods

The use of three analytical techniques for forensic investigation of synthetic polymers is described. These techniques are: pyrolysis infrared spectrometry (PyIR), pyrolysis gas chromatography (PyGC) and energy dispersive X-ray micro probe analysis (EPMA). Whereas the first two methods have been described previously, the microanalytical procedure is new. It may be used in combination with one of the other two techniques for the discrimination between polymer samples.     

Potential problems with the interpretation of hair analysis results

Due to differences in hair growth rate depending on anatomical region, age, gender, ethnicity and interindividual variability, interpretation of parent drug or/and metabolite concentrations in hair is not easy. Furthermore, as drug incorporation mechanisms into hair matrix is not yet fully understood, it is rather difficult to extrapolate details on time and dose from hair segment analysis. If incorporation sources other than from bloodstream (skin secretions and/or external/environmental contamination) are considered, interpretation becomes even more complicated. For evaluating possible passive contamination, it is essential to consider specific identification of metabolites, use of metabolite-to-parent drug ratios, assays of decontamination washes and analysis of specimens collected from other body parts. Cosmetic hair treatment, natural and artificial hair colour, differences in hair structure and specificity of analytical methodology may represent other bias sources affecting concentrations of drugs in hair. A suitable cut-off level related to the LOD will allow correct identification of drugs or metabolites in hair. Regarding the performance of different hair testing laboratories, little information is available at this time to what extent test results are comparable and their interpretation is consistent. Frequency of drug consumption and time intervals between multiple consumption or lag time between consumption and appearance in the hair has not been fully investigated and needs further research.     

浓缩DNA法结合miniSTR分型技术检验微量DNA

目的优化低拷贝数DNA STR分型方法。方法对采用磁珠法或Chelex-100法提取DNA,Identi-filer试剂盒扩增,未获得分型结果的日常检案检材,采用物理浓缩法或过柱浓缩法浓缩DNA,采用miniFilerTM试剂盒再次扩增分型。结果 127例检材中,47例磁珠法提取DNA未获得分型的样品,分型成功率为36%;80例Chelex-100法提取DNA未获分型的样品,分型成功率为30%。结论采用浓缩法和miniFilerTM试剂盒,可以提高日常检案中低拷贝数检材的STR检验分型成功率。     

Empirical analysis of solid state disk data retention when used with contemporary operating systems

Data recovery techniques for platter-based disk drives have remained rather static due to the dominance of the hard disk for the last two decades. Solid State Disk drives have differing storage and recall functionality from platter-based disks and require special care when attempting data recovery. Manufacturers have varying implementations of garbage collection in each drive, which affects the amount of data retained on the disk. This paper presents an analysis of solid state disk data retention based off of empirical evidence of 16 different disks. It also discusses the data recovery problem faced by forensic examiners due to the ATA8 TRIM command, which can sanitize disks in seconds. The experiment shows that without TRIM, nearly all data is recoverable, but with TRIM enabled only up to 27% of blocks were recoverable dependent on the controller manufacturer.     

巨额财产来源不明罪证明责任实证分析-以100例司法裁判为研究样本

巨额财产来源不明罪证明责任的司法适用分歧,折射了关于证明责任和无罪推定之间关系认识的模糊不清。巨额财产来源不明罪中被告人应当承担的证明责任,不宜理解为“提供证据的责任”,而应阐释为“较大可能性”或“优势证据”标准的“说服责任”,这一结论的得出,是基于无罪推定原则的合理限制角度,充分考虑该罪立法目的以及在我国的司法适用情形,从比例原则的角度进行的正当性考量。     

Malware categorization using dynamic mnemonic frequency analysis with redundancy filtering

The battle between malware developers and security analysts continues, and the number of malware and malware variants keeps increasing every year. Automated malware generation tools and various detection evasion techniques are also developed every year. To catch up with the advance of malware development technologies, malware analysis techniques need to be advanced to help security analysts. In this paper, we propose a malware analysis method to categorize malware using dynamic mnemonic frequencies. We also proposed a redundancy filtering technique to alleviate drawbacks of dynamic analysis. Experimental results show that our proposed method can categorize malware and can reduce storage overheads of dynamic analysis.     

Partial order scalogram analysis with base coordinates (POSAC): Its application to crime patterns in all the states in the United States

In this paper, a new nonmetric method called POSAC is presented and illustrated through an analysis of the crime patterns of all the states in the United States. POSAC is a graphical technique for the display of multivariate data in a two-dimensional space. It maps the rows (e.g., states) of a matrix in a way that maximizes the preservation of theirpartial order, with similar states located in close proximity on the map. POSAC is based on the partial order among observations rather than their actual magnitude. POSAC seems to bear the same relationship to the principal-component analysis (PCA) as that borne by the median to the arithmetic mean. As a matter of fact, POSAC is a form of ordinal factor analysis. Its advantage over PCA is its robustness to the data. The technique enables observations and variables to be studied simultaneously. Seven index crime categories are analyzed. In order to demonstrate the utility of POSAC in detecting changes in crime patterns over time, we included in our analysis three selected years: 1944, 1965, and 1987. The results for the year 1987 are compared to those obtained by PCA.     

图像分析技术在测定细胞DNA含量推断死亡时间中的若干问题

图像分析技术为法医学早期死亡时间推断提供了一种新的方法,但目前仍有许多局限,本文将重点讨论标本的取材及固定、涂片或切片的选择、细胞群聚和重叠的处理、参考细胞核及门槛问题,以及个体差异对图像分析的影响及相应的解决方法。     

A comparative analysis of media reports of U.S. parricide cases with officially reported national crime data and the psychiatric and psychological literature

This article is a content analysis of 150 unique cases of children killing parents in the United States as reported in the electronic news media. The accuracy of online coverage of U.S. parricide incidents is assessed using two types of resources: officially reported national statistics on known parricidal incidents and the psychological and psychiatric literature on matricide and patricide. Comparisons of news accounts of media-reported U.S. parricide cases with Supplementary Homicide Report data indicate that electronic media coverage of parricide cases focused on the more sensational and unusual parricides. Analyses of these media accounts by offender age found 13 significant differences between juvenile and adult offenders. Ten of these 13 differences related to motive and Heide's parricide offender types (severely abused, severely mentally ill, and dangerously antisocial) and were consistent with the mental health-related literature in this area. The limitations and directions for future research are discussed at length.