The printed materials used in cases of stalking, intimidation, etc. is assumed to be black texts printed by inkjet printers. We examined discrimination of black printed materials by dye inks in an analysis of dye components using TLC and HPLC-PDA, analysis of solvents components using GC/MS, and analysis of trace elements using ICP-MS. We also attempted to classify the samples using multivariate analysis based on the analysis results, and to identify the manufacturer. In this study, a total of 17 samples were analyzed, including inks manufactured by Canon, EPSON, Brother, and their compatible inks. One hundred twenty five of the 136 pairs of samples were distinguished by TLC, and One hundred twenty nine of the 136 pairs of samples were distinguished by HPLC-PDA. HPLC-PDA can perform separation analysis for all samples and therefore seemed a better method. GC/MS detected components such as 2,2-sulfonyl diethanol, triethanolamine, and tetraethyleneglycol. Samples were distinguished by 109/136 patterns by mainly using these components as indicators. The quantitative analysis of Li and Cu was performed by ICP-MS, and the concentration ratio of those two elements (Li/Cu) was calculated. Samples were distinguished by 120/136 patterns by this ratio. Samples were distinguished by 133/136 patterns by combining all analyses. In many cases, it is possible to distinguish inks by dye components, but inks with different model numbers may show similar results. Thus a combination of GC/MS and ICP-MS should be used for judgment. In addition, by conducting principal component analysis and cluster analysis based on the area values of each detected component by GC/MS and the detected intensities of Li and Cu by ICP-MS, it is possible to estimate the manufacturer.

Body fluid identification from crime scene evidence is crucial to determine the type of crime and to verify the victim’s testimony. We previously developed the multiple body fluid-targeted multiplex RT-PCR assay (MM) for simultaneous discrimination of blood, saliva, semen, vaginal fluid and nasal secretion. That procedure enabled precise and comprehensive identification of forensically relevant body fluids, especially in unknown or mixed biological samples. Alternatively, it is possible to narrow down the body fluid type by creating a case summary and performing a presumptive test for the expected body fluid and followed by a confirmatory test. In the present study, single body fluid-targeted multiplex RT-PCR assays (SM) were developed for the individual identification of blood, saliva, semen, or vaginal fluids. The repeatability of SM results was evaluated by using the pooled cDNA of each targeted body fluid and comparing it with the results of MM. Then, the peak height and detectability of each marker were compared between MM and SM on individual mixed and unmixed body-fluid stains. Like MM, the normalized values of SM were well reproduced in repeated electrophoreses. The positivity of the body-fluid markers was also well reproduced in repeated PCR amplifications. The average peak heights of some markers were significantly higher in SM than in MM. The detectability of SPTB, MUC7, and SERPINB13, which showed lower average peak heights among body fluid markers, was improved in SM. Comparable positive detection of other markers that showed sufficient amplification was found in SM and MM. The identification of targeted body fluid was performed based on the criteria we previously proposed, showing highly specific results. In conclusion, SM and MM can be performed individually or simultaneously based on the sample condition or case summary in order to precisely identify body fluid samples in forensic laboratories.

Earth drilling is a method of making trenches for constructing piles. In this method, bentonite slurry is used to protect the porous wall during the trench excavation. The sludge from this method is defined as industrial waste under Japanese law. Nevertheless, some companies dispose of construction sludge illegally. However, there are no analytical methods for identifying bentonite sludge. Bentonite must be detected to identify sludge in suspicious soils. But smectite clay is the main component of bentonite, and is often contained in soil. It is unknown whether the smectite in soil interferes with detection of bentonite from sludge. To detect bentonite in construction sludge, we analyzed soils spiked with bentonite at various concentrations using X-ray diffraction. We also examined construction sludge from earth drilling with or without HCl treatment. The bentonite peak was observed in all spiked samples, even when the bentonite concentration was 20% and the soil contained smectite. In construction sludge, bentonite peaks were observed without HCl treatment; however, they were smaller than expected. HCl treatment removed the chlorite peak, which was near that of bentonite, allowing for easier identification of bentonite peaks. This study provided new insights into the forensic analysis of environmental crime samples.

In Accidents that the car collided with the person lying on the road, the case fatality rate and hit-and-run rate were high, so the recognition of the location where the victim could be found was often the issue. There was also the cognitive error due to the driver’s belief that a person could not lie on the road. There were many researches on the driver’s visibility in pedestrian accidents, whereas there were few studies conducted on those of the person lying on the road. In this research, we conducted the driving experiment to examine whether the visually recognizable distance of the person lying on the road in night driving changed depending on the speed. There were no significant difference of the visually recognizable distance between slow speed, 40 km/h, and 60 km/h.

Age estimation by use of DNA methylation rate have recently been one of the hottest topics in forensic genetics, thus many age prediction models have been developed. The age prediction model developed by Bekaert et al was evaluated as the best method comparing six blood-based models in 2019. In this study, Bekaert's age estimation model was validated with 143 Japanese blood samples (98 living and 45 dead blood samples). The difference between duplicate measurement of DNA methylation rate with pyrosequencer was less than one-year per one-gene in age prediction result. Overall mean absolute error (MAE) was 3.24, and root mean square error (RMSE) was 4.13. MAE of the elder group was larger than that of the young group. No statistically significant difference in absolute prediction error was observed between living and deceased or male and female blood samples. Furthermore, a novel model was developed with support vector regression. The MAE and RMSE were 3.49 and 4.51 for test set, respectively. In total, 200 ng of pre-bisulfite-treated DNA was essential to perform these predictions. To reduce the required amount of DNA, new models based on only ELOVL2 methylation rate requiring only 40 ng of DNA were also developed. The MAE and RMSE were 3.15 and 4.20 for test set, respectively. These results suggest that both Bekaert's age estimation model and our novel model have great potential in estimating one's age on forensic practices with some points to note.

In Japan, possession of germinable cannabis seeds for cultivation purposes is subject to prosecution. Cannabis seeds are marketed after being treated to prevent germination (heated or crushed). Currently, forensic examination of cannabis seeds is conducted by cultivating the seeds after germination tests for several weeks and then performing morphological observation and chemical analysis on the true leaves. In this study, we attempted to construct a rapid and simple method for the identification of cannabis seeds by combining the color reaction using 2,3,5-Triphenyl-2H-tetrazolium Chloride (TTC), a reagent that discriminates between living and dead cells, and DNA testing using a commercially available simple kit.

In the case of a fire incident such as arson, the combustion experiment that reconstructed the fire scene will be conducted to clarify the facts. However, various problems such as construction costs and securing an experimental environment must be dealt with. Therefore, the purpose of this study is to utilize fire simulation for the investigation of fire incidents. In this study, combustion experiments and FDS (Fire Dynamics Simulator) simulations assuming gasoline arson in the kitchen, which have not been reported so far, were conducted and compared. Next, the observation of fire damage using the accumulated heat-flux was evaluated by a newly developed analysis tool for visual evaluation. The simulation results such as burning behavior, temperature changes, and the burned away phenomenon of the door showed good agreement with those experimental results. Burning behavior in the kitchen, that couldn't be observed in the combustion experiment were grasped in detail in the simulation. Furthermore, the relationship between the fire source and the fire damage on the floor, which couldn't be explained only by the observation results after extinguishing the fire, could be reasonably explained by the visual evaluation of burning behavior and the accumulated heat-flux in the kitchen by using the simulation. Therefore, the fire simulation was shown to be an effective tool for analyzing fire phenomena.

Pull-up reduction feature (PUR) has been available since the update of the Data Collection Software version to 4. There is concern that data obtained from utilizing PUR might have some impact on the review and interpretation in STR typing by forensic biologists, because PUR changes the height of peaks under specific conditions. In this study, we first investigated the amount of reduction in peak height by PUR, then impact of PUR on remarkable peaks (e.g., an artifact comprised of a stutter peak and pull-up) was investigated. Fundamentally, the amount of reduction in peak height between PUR disable and enable showed a positive correlation with the parent peak height except for fluorescent dye red to purple. It was also confirmed that PUR functioned against the stutter peak shared with pull-up and irregular shape peak due to detected on the edge of an allele peak. For the mixture sample, the PUR impacted the minor contributor's allele peak which up to approximately 23.1% of the parent peak. Our data showed that the characteristics of PUR in reviewing artifacts and interpreting the STR typing should be taken into consideration.

The concealed information test (CIT) is a psychophysiological memory-detection technique. The judgment to assess whether an examinee recognizes crime-relevant information is based on the difference in autonomic responses between the crime-relevant information and the crime-irrelevant information. The present study examined the within-questionnaire consistency of the differential physiological responses, which is a key point in the above judgment. The mock theft CIT data obtained from 167 participants were modeled into three possible models, and Bayesian estimation of parameters and model selection were performed. Results of model selection implied that participants in the encoding group were not clearly divided into high consistency responders and non-responders. Bayesian estimates of parameters revealed that the within-questionnaire consistency of the differential physiological responses had different characteristics among the physiological measures. Most participants showed high consistency for heart rate and respiratory speed, while some participants show low consistency for skin conductance response, respiratory amplitude, and respiratory rate.

In this study, the excretion profiles of etizolam (EZ) and its main metabolites including conjugates in urine have been investigated to obtain fundamental information for proving the drug intake in the cases of drug-related crimes. Urine specimens were collected from three volunteers during about 200 h after a single oral ingestion of EZ (1 mg). Three glucuronides (including diastereomers) of 8-α-hydroxyetizolam (EZ-M3) and 1-hydroxyetizolam (EZ-M6) along with free EZ-M3 and EZ-M6 were detected for the first time directly as metabolites of EZ using liquid chromatography-tandem mass spectrometry with a C18 semi-micro column. EZ, EZ-M3 and EZ-M6 were quantified using the authentic standards, and urinary concentrations of the glucuronides were calculated based on the increased amounts of EZ-M3 and EZ-M6 after enzymatic hydrolysis. The quantitative results demonstrated that the ratios of amounts of EZ-M3 and EZ-M6 including their glucuronides excreted in urine to the dose ranged about 18-22% and 9.5-14%, respectively, although that of the unchanged EZ was less than 0.3%. The glucuronide of EZ-M6 reached the highest concentration (more than 200 ng/mL) of metabolites in the early period (within 12 h) after intake. However, in a latter period (24 h or later) after intake, the concentration of EZ-M3 or its glucuronides was higher than that of glucuronide of EZ-M6 in most of the samples. The conjugation percentages of EZ-M3 and EZ-M6 were calculated to be approximately 50% and 98% or higher, respectively. This study suggested that the detectable duration of EZ-M3 (approximately one week after intake, Limit of detection: 0.05 ng/mL) is longer than those of EZ and EZ-M6. In addition, the enzymatic hydrolysis prior to analysis is expected to prolong the detectable duration of EZ-M3 slightly.