Micro X-ray fluorescence spectrometry (μXRF) was applied to the non-destructive determination of trace elements in glass fragments. In μXRF, if the thickness of glass sample was not enough, the peak intensities decreased. The influence of this effect on forensic glass discrimination is not clear. In addition, the rarity of glass distributed in Japan has not reported yet. Therefore, in this study, we examined the influence of the peak intensity decrease on forensic glass discrimination and evaluated the rarity by constructing new databases including 921 refractive index (RI) data and 147 elemental peak intensity ratios (elemental ratios, Ca/Mg, Ca/K, Ca/Ti, Ca/Fe, Fe/Zr, Sr/Zr) data. As a result, along with the decrease of the glass sample size, the elemental peak intensity (such as Mg, K, Ca) and the elemental ratios (Ca/Mg, Ca/K) kept almost constant, but the elemental peak intensity (such as Sr, Zr) decreased and the elemental ratios (Fe/Zr, Sr/Zr) changed. The elemental ratios of 1 mm or more particle size were equivalent to those of infinite thickness. On the other hand, even though the elemental ratios of 1 mm or less particle size changed, the elemental ratios could be compared by preparing the samples with the same conditions between them for comparison. The maximum frequency of RI was 10.8 %, and the maximum frequencies of elemental ratios were 34.5 % for Ca/Mg and 26.4 % for Sr/Zr, and the other elemental ratios were widely distributed in the database. The likelihood ratio for RI increased as the number of the match fragments increased, and the likelihood ratio for elemental ratios increased as the number of the discrimination factors increased. Finally, the restrictions on forensic glass discrimination using μXRF were clarified and the rarity of glass distributed in Japan was evaluated quantitatively.

 A newly encountered designer drug “N¹-cyclopropylmethanoyl-lysergicaciddiethylamide (1cP-LSD)” is an acylated derivative of LSD. Based on the structural characteristics, 1cP-LSD is expected to be readily metabolized to LSD, which can make it difficult to discriminate between intakes of 1cP-LSD and LSD. In this study, to obtain the fundamental information needed for proving intake of 1cP-LSD, the metabolism experiments were performed using human liver microsomes (HLM). 1cP-LSD and its 10 metabolites were detected in HLM reaction mixtures of 1cP-LSD using liquid chromatography-high resolution-tandem mass spectrometry with a C18 semi-micro column and the time-course changes in concentrations of them were observed during the first 120 minutes of the reactions. The results demonstrated that 1cP-LSD rapidly decreased in microsomal mixtures (half-life time: 5 min) and a metabolic reaction by carboxylesterase, expressed abundantly in liver, was mostly responsible for the decrease. This short half-life of 1cP-LSD implied biological samples such as urine and blood should be collected from suspects as soon as possible after intake for detecting unchanged 1cP-LSD, which can lead to the proof of intake. Four out of 10 microsomal metabolites (hydroxy-, N-desethyl-, N⁶-desmethyl and N-desethyl-N⁶-desmethyl metabolites) could also be useful indicators for proving intake of 1cP-LSD since they retain a cyclopropylmethanoyl group. Especially, the N⁶-desmethyl metabolite appeared to be a more appropriate indicator because it could be detected in microsomal mixtures over longer periods.

 Cannabidiol (CBD), an uncontrolled cannabinoid in marijuana, is readily converted to the controlled Δ⁹- and Δ⁸-THCs under acidic conditions. In this study, we monitored the time-course conversion of CBD into the two THCs using easily available acids and solvents by gas chromatography-mass spectrometry. Placing CBD (3.3 mg/mL) in 4.2 mM sulfuric acid-glacial acetic acid solution at room temperature resulted in the production of Δ⁹-Tetrahydrocannabinol (Δ⁹-THC) after 3 hours, followed by Δ⁸-THC after 96 hours. The conversion continued, and their relative abundance was Δ⁹-THC>CBD>Δ⁸-THC after 192 hours. Elevating the sulfuric acid concentration to 42 mM promoted the conversion to where CBD depleted in 3 hours, Δ⁹-THC production peaked (and started to decline) at 12 hours, and Δ⁸-THC became the major constituent at 100 hours. Replacing sulfuric acid with muriatic acid showed the similar time-course conversion. The THCs/CBD ratio varies under acidic conditions; this ratio can be used as an indicator for identifying the product lots of liquid drugs containing THCs converted from CBD. Ethanol, alternative solvent to glacial acetic acid, kept CBD unchanged with 42 mM sulfuric acid for 192 hours at room temperature, but conversion into Δ⁹-THC was observed after 6 hours when heated at 70℃. Without an acid catalyst, CBD was stable under heating cycles from 60℃ to 130℃ in an electric vaporizer. Thus, the unintentional production of THCs seems unlikely only by heating a commercial CBD product. The CBD-to-THCs conversion also yielded several by-products. Among them, possible Δ⁸-iso-THC was detected under all 12 combination conditions (two catalytic acids and six solvents) investigated in this study. Additionally, the use of alcohol solvents produced alcohol adducts of the THCs. Detection of by-products therefore can provide more solid information for identifying the product lots and estimating the condition of CBD conversion.

　Short Tandem Repeat (STR) typing plays an important role in forensic science. Currently, many laboratories return the residual unextracted DNA evidence sample to police stations according to regulations in Japan. However, it has not been clarified how well the results of the original DNA analysis can be reproduced in the case of retest of trace or mixed DNA from remaining unextracted DNA evidence samples. In this study, simulated touch DNA samples were prepared, and STR typing was performed to verify the reproducibility of the results. Touch DNA samples were produced by having 25 individuals hold a doorknob, a 50 mL tube, and another personʼs clothing tightly for 1 minute each. These touch DNA samples were divided into two parts and STR typing was performed on each and the results were compared. The results indicated that the number of alleles and peak heights may vary between the original DNA test and retest, and the results are not necessarily identical. The discordance in the results may be due to changes in the amount of DNA extracted from the material, changes in the mixture ratio, or the appearance of alleles of unknown origin. This is due to the heterogeneity of touch DNA samples collected by swabbing, etc., and is not considered to negate the reliability of the respective result of DNA tests. The reproducibility of results when re-extracting from residual touch DNA evidence sample was expected to be difficult due to trace or mixed DNA, but to our knowledge, there are no previous reports verifying this fact. This study reveals for the first time the reality of this situation.

 The PCR amplification of STR loci typically produces a minor byproduct called minus stutter (or plus stutter) that is one repeat unit shorter (or one repeat unit longer) than the original product. These stutters cause some problems that affect the result of STR typing and complicate when comparing results of STR typing. It is necessary to remove the stutter in the forensic STR typing. Minus stutter is filtered out automatically by setting of the analysis software. On the other hand, plus stutter at most loci in STR Kits does not have such setting and it is in particular difficult to distinguish between the original peak and stutter peak.

 In this study, we calculated plus stutter ratio for each long allele (25 and over) at D18S51 and compared it with minus stutter ratio. In addition, we also calculated plus stutter ratio using various STR Kits or changing the annealing temperature conditions.

 The results showed stutter ratio and the number of repeat units were in positive correlation and stutter ratio was not affected by the STR Kit. Plus stutter ratio had more variability than minus stutter ratio regardless of the number of repeat units or STR Kit. It showed a clear difference between minus stutter and plus stutter. The results also suggested minus stutter ratio and annealing temperature were in positive correlation, but plus stutter ratio and annealing temperature were not in positive correlation. It seemed therefore likely that minus stutter may be possible to set a threshold for each allele, but it is difficult to set a threshold in the same way for plus stutter.

 Interpretation of crime stain profiles is one of the challenging tasks of forensic scientists. Before using the probabilistic genotyping system, forensic scientists should interpret crime stain profiles using analytical and stochastic thresholds. According to the guidelines presented by the Scientific Working Group on DNA Analysis Methods, these thresholds shall be based on and supported by applicable internal validation studies. In this study, we performed the internal validation study of our DNA typing system to determine these thresholds. A total of 350 DNA samples and 11 negative controls were amplified using GlobalFiler^TM PCR Amplification Kit with 30 cycles and PCR products were then analyzed on a SeqStudio Genetic Analyzer. As a result, the analytical threshold was set to 110 RFU, which has high sensitivity to obtain almost full profiles of 0.063 ng DNA, and has high specificity not to detect most of the pull-up and drop-in peaks. The stochastic threshold was set to 890 RFU allowing a 1% probability of allelic drop-out based on logistic regression. These thresholds are useful for interpreting crime stain profiles in our GlobalFiler system.

 We examined the stability of Δ⁹-tetrahydrocannabinol acetate (Δ⁹-THC-OAc) and Δ⁸-tetrahydrocannabinol acetate (Δ⁸-THC-OAc) in e-liquid products. Eight samples were heated at 30℃ for 28 days and one of them was heated at 70℃ for 2, 4, 8, 10, and 15 days. Residual ratios of Δ⁹-THC-OAc and Δ⁸-THC-OAc were evaluated by gas chromatography with flame ion detection and their degradation products were examined by gas chromatography/mass spectrometry (GC/MS). Some samples were tested for solubility in hexane and were submitted to GC/MS analysis to detect propylene glycol and glycerol. After a 28-day incubation at 30℃, Δ⁹-THC-OAc was slightly decomposed (residual ratio: 84.5–94.2%) but Δ⁸-THC-OAc was almost stable (residual ratio: 95.2–108.9%). Heating at 70℃ decomposed not only Δ⁹-THC-OAc but also Δ⁸-THC-OAc. The decomposition proceeded rapidly in the initial 2 days then slowly until 15 days later. The degradation products, four putative one-oxygen-atom adducts and cannabinol, were detected but deacetylated products (Δ⁹-tetrahydrocannabinol and Δ⁸-tetrahydrocannabinol) were not detected. All the samples tested were completely dissolved in hexane differently from propylene glycol and glycerol. Propylene glycol and glycerol were not detected from the samples completely dissolved in hexane. This study indicated that deacetylation of Δ⁹-THC-OAc and Δ⁸-THC-OAc did not proceed when the sample did not contain propylene glycol and glycerol.

 The Scientific Working Group on DNA Analysis Methods (SWGDAM) validation guidelines for DNA analysis method indicate that when material modifications are made to an existing procedure that may affect the results of the analysis, the concordance between the results before and after the modifications should be confirmed. In this study, we modified our conventional procedure for mitochondrial DNA (mtDNA) analysis by changing the mtDNA quantification and sequence product purification methods along with and without changing the version of the data collection software and/or sequencing analysis software. We performed mtDNA analysis using the four modified procedures and ensured the concordance between the results obtained before and after the modifications. The sensitivity was also confirmed to be comparable among the conventional and all the modified procedures. Therefore, we concluded that the modifications can be adopted in the procedures for our mtDNA analysis.

 Cyanide is a gaseous poison which is liberated from cyanide compounds such as potassium cyanide. In spite of high toxicity, cyanide compounds are easily accessible for industrial use, and some contamination cases of cyanide into beverages have occurred. For analysis of cyanide, various analytical methods such as colorimetric methods have been reported. Among those, headspace-gas chromatography-nitrogen phosphorus detection (HS-GC-NPD) is known for its easy pretreatment method and high quantitation ability. The application of HS-GC-NPD analysis to cyanide in blood specimens have been reported by many groups. However, comparison results of some experimental manipulations, such as addition of acid, syringes used for introduction of samples to the GC, and amount of sample introduced into the GC are not clear. In addition, there is no detailed description about application to beverage samples. In this work, we have investigated some experimental manipulation of manual HS-GC-NPD and applied the optimized method to beverage samples. After the optimization, the addition of acid with micropipette in open system and introduction of 100 μL of headspace gas into GC with gastight syringe are recommended. For beverage samples, although variations were larger than standard samples, those variations could be compensated by use of acetonitrile as an internal standard.

　For forensic science, vomit identification is essential for crime scene reconstruction in various crimes, such as murder, abuse and drug poisoning. In order to develop a rapid and simple method for vomit identification, we modified the protocol for pepsinogen I (PGI) and pepsinogen II (PGII) detection kits based on latex agglutination turbidimetric immunoassay for clinical examination. Although these kits are assumed for using expensive automated biochemical analyzers, we examined the analysis on a general absorption spectrometer. As a result, PGI and PGII could be detected in up to 1000-fold diluted human gastric juices and mock casework samples by our modified method. However, cross-reactions with urine for PGI and semen for PGII were observed. If urine and/or semen is considered to be mixed in the casework samples, urine and/or semen tests should be performed in addition to PGI and PGII tests. Aged gastric juices stored up to 12 months were also detected, suggesting that the present method could be applicable to aged samples. Because PGI and PGII can be detected within approximately 1 hour by simple operations using an absorption spectrometer, the present method has the potential to be applicable to forensic caseworks as a new tool for vomit identification.

 This article aims to evaluate estimation of the postmortem submersion interval (PMSI) for cadavers recovered from the Pacific Ocean in the South Kanto area of Japan. Data were collected from crime scene reports in the 3rd Regional Coast Guard Headquarters over a 11-year period. Approximate time of PMSI was available for 72 cases with the decomposition stage from photo pictures at the scene. No visible changes in the skin of the hands and feet counted from 27 cases, wrinkling and discoloration in 28 cases, and degloving in 17 cases. The average (±S.D.) of accumulated degree days (ADD) was 2.0±3.3, 24.5±19.1, 164.0±112.5, respectively. As minimum ADD, wrinkling and degloving were expected to be formed in 9.4 and 77.8, respectively, which corresponded to a half day and four days at 20°C of sea water temperature. In comparison with other findings, degloving was accompanied by bloated abdomen, sloughing of hairs, and peeling of nails. The characteristic changes of the hands and feet were helpful to estimate PMSI for submerged cadavers. We expect to apply this finding to criminal investigation at the scene.

 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.

 The stability of Δ⁹‒tetrahydrocannabinol acetate (Δ⁹‒THC‒OAc) and Δ⁸‒tetrahydrocannabinol acetate (Δ⁸‒THC‒OAc) in e-liquid during storage was investigated. Δ⁹‒THC‒OAc liquids in cartridges were stored at 80℃ or 30℃ for 28 days. The relative concentrations of cannabinoids in the liquids were measured by gas chromatography with flame ionization detection. Δ⁹‒THC‒OAc decreased during storage at either temperature. Δ⁹‒THC, a minor impurity, also decreased. Δ⁸‒THC‒OAc liquid in a cartridge was stored at 80℃ for 57 days. The concentration of Δ⁸‒THC‒OAc and Δ⁸‒THC, a minor impurity, did not change during that time. Cannabinol acetate increased in all liquids, and unknown products were also detected by gas chromatography/mass spectrometry (GC/MS). The Δ⁹‒THC‒OAc and Δ⁸‒THC‒OAc liquids were subjected to GC/MS to detect representative diluents, glycerol, propylene glycol, and polyethylene glycol 400, but none of these were detected.