The inhibition of human salivary α-amylase activity in forensic samples can lead to false negatives in α-amylase activity-based saliva screening tests. This study aimed to develop and validate an α-amylase inhibition-resistant saliva presumptive test using the Ohta and Ohmura’s modified blue starch agarose plate (OhM) method, incorporating bovine serum albumin and calcium chloride. To assess the effectiveness of the OhM method, we compared its positive detection rate to that of the conventional method through various validation experiments. In a mixture experiment using commercial beverages, the OhM method successfully detected positive reactions in samples that tested negative using the conventional method. Our results demonstrate that the OhM method is a practical and sufficient technique for identifying saliva in forensic samples that may be subject to α-amylase inhibition.

To estimate the heated damage of gypsum board used as ceiling and wall in the investigation of building fire, the chemical composition and appearance of heated gypsum were examined. Three patterns of gypsum samples heated by cone calorimeter and electric furnace were prepared, and the chemical composition of the gypsum was analyzed by X-ray diffraction.

Calcium sulfate dihydrate in heated gypsum board was changed through two dehydrate reactions and finally turned into anhydrate via hemihydrate. The three layered structures with different colors appeared at the cross section of gypsum by watering after heating. The thicknesses of the three layers corresponded to the proportion of anhydrate, hemihydrate and dihydrate of calcium sulfate in gypsum board, respectively. Therefore, observation of three layers of gypsum after fire and fire extinction can help to estimate the degree of damage by fire.

In this study, we performed simulations to evaluate the usefulness of parentage tests using likelihood ratios (LRs) calculated considering mutation and silent alleles for the Japanese population. In the simulations, genotype data of parents and a child and those of unrelated persons were generated randomly for GlobalFiler autosomal short tandem repeats and LRs were calculated for them. The results indicated that high LRs were calculated by considering mutation and silent alleles for most of the genotype data of families with mutation and/or silent alleles. We compared calculated LRs between for trios and for duos; with a few exceptions, the LRs calculated for trios were greater than those calculated for duos. We also evaluated the distribution of LRs calculated for unrelated persons and found that in most cases of unrelated persons, the LRs were less than 1, and for the majority, 0. The results of this study will contribute to the practical introduction of calculation and evaluation of LRs considering mutation and silent alleles in parentage tests.

Identification of vaginal secretions from a suspect’s penis, fingers, sexual toys, or other possessions is crucial evidence in proving sexual crimes. A decade earlier, we focused on the Lactobacillus species present in the vagina and developed a method for identifying vaginal secretions by the relative quantification of Lactobacillus DNA, which was introduced into forensic practice. In this study, after confirming the feasibility of this method on QuantStudio 5, a different real-time PCR device from that used in the development of the method, we examined the annealing temperature to improve the specificity for vaginal secretions. Increasing the annealing temperature to 63 °C (compared to 55 °C in the original development study) reduced the non-specific amplification caused by DNA from microorganisms closely related to the Lactobacillus genus present in saliva, providing a clearer distinction between vaginal secretions and saliva than that obtained during the development phase. Furthermore, based on the comparison of DNA extraction methods, it was recommended that the DNA solution used in this method be purified from lysozyme-treated solution and then PK- or DTT-treated solution. The rectal mucosa samples from women contained a significant number of Lactobacillus and were difficult to distinguish from vaginal secretions. In conclusion, although caution is required when anal intercourse is suspected, this improved method with higher annealing temperature is anticipated to be increasingly used in forensic practice, because it is not only simple and highly sensitive but also has improved specificity.

False positivity is one of the major problems in interpreting assessment results. This study aimed to confirm the association of enzyme-contained kitchen detergents with false positives in saliva presumptive tests with the blue starch agarose plate method. Ten commercially available kitchen detergents were utilized as stain samples in the test. Six detergents (i.e., CHARMY Magica Enzyme Plus Orange Fragrances, CHARMY Magica Enzyme Plus Fresh Peach Fragrances, CHARMY Crysta Clear Gel, Cucute Lakumist, former products of CHARMY Magica Enzyme Plus Orange and Grapefruit Fragrances) generated false-positive reactions in the concentration ranging from undiluted to 64-fold diluted samples. Our results reveal that forensic experts should carefully interpret positive results of the blue starch agarose plate method from potentially detergent-mixed samples (e.g., glasses and chopsticks).

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.

日本法科学技術学会誌第30巻第1号に誤りがありました．

下記の通り訂正します．

(1) P104（Table 1）

誤
Compound　Precursorion　Product ion　FV　CE
　　　　　　(m/z, [M+H]⁺)　　(m/z)　　(V)　(eV)
Δ⁹-THC-COOH　　345　　　299 (QT)　　114　21
　　　　　　　　　　　　　327 (QL)　　114　13
Δ⁸-THC-COOH　　345　　　327 (QT)　　148　17
　　　　　　　　　　　　　299 (QL)　　148　21

正
Δ⁸-THC-COOH　　345　　　299 (QT)　　148　21
　　　　　　　　　　　　　327 (QL)　　148　17
Δ⁹-THC-COOH　　345　　　327 (QT)　　114　13
　　　　　　　　　　　　　299 (QL)　　114　21

(2) P105（Fig. 2 最上段および2段目），P106（Fig. 3 最下段），P107（Table 2aおよび2b）， P108（Table 3aおよび3b）

誤　Δ⁹-THC-COOH
正　Δ⁸-THC-COOH

誤　Δ⁸-THC-COOH
正　Δ⁹-THC-COOH

(3) P105（Fig. 2 最下段）

誤　CE, 27 eV
正　CE, 17 eV

(4) P107（右カラム 4, 6行目）

誤　Δ⁹-THC-COOH
正　Δ⁸-THC-COOH