Mie Prefectural Police

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.

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.

Inform ation T est Naohiro Yam am oto (Forensic Science Lab, Yam ag ata prefectural police H.Q .)Key Words：Concelaed Inform ation T est, within a set judg m ent m ethod, kernel density estim ation

Modeling the curving motion of humans in actual environment is rarely done because of the complexity and variability of the turning motion. In this study, various gait motions, including straight, round corner, and circular walks, were recorded and analyzed using factor analysis. As a result, we successfully extracted several factors that represent turning motions, such as long stride motion, turning motion led by the inner leg, and turning motion led by the outer leg. In particular, we found that the natural curving motion, which is a motion that results when turning around a round corner, is widely and continuously distributed on the factor space. Although several typical stepping strategies were reported by related studies, we found that the stepping motion changes between straight and turning gaits in the factor space during natural curving motions. Thus, the classification of curving motion into several typical distinct stepping patterns is probably insufficient to understand the natural curving motion. Furthermore, natural curving motions that comprise circular curving motions that were believed to represent typical curving motions was not validated. On the other hand, this result also suggests the possibility of generating curving motions for a physical assistant robot by combining straight gait and circler curving motion.