In-line solid phase extraction capillary electrophoresis-mass spectrometry (In-line SPE-CE/MS) has been developed for the screening of methamphetamine (MA) and amphetamine (AP) in hair. A Teflon tube packed with solid phase extractant was connected In-line to the capillary. The detection sensitivity of this method was about 100 times higher than that of common stacking methods. Since the filtrate of digested hair samples could be injected directly into the In-line SPE-CE/MS system, enzyme-based digestion techniques were investigated for the pre-treatment of hair samples. As a result, we found that hair was mostly digested with proteinase K, along with dithiothreitol, urea and TNE buffer (pH 8.0, 10 mM Tris, 100 mM NaCl, 1 mM EDTA) at 55℃ in an hour. Finally, hair samples spiked with MA and AP were analyzed by the developed In-line SPE-CE/MS method. The limits of quantification were 0.08 ng/sample for MA and 0.18 ng/sample for AP. In-line SPE-CE/MS is useful for the screening of MA in hair because MA in a single 1-cm hair strand is detectable at the concentration of 1.6 ng/mg hair.
We have evaluated the identification and differentiation abilities of three portable spectrometers (TruNarc: Raman spectrometer, Target-ID: infrared spectrometer, NIRSCAN-MKII: near-infrared spectrometer) for on-site drug screening. Identification abilities were evaluated using samples containing methamphetamine (MA) and cocaine (COC), including case samples and mixtures of these drugs with diluents. Differentiation ability was evaluated using case samples that did not contain MA or COC and compounds having similar chemical structures to MA and α-pyrrolidinovalerophenone (α-PVP). All three spectrometers commonly showed acceptable true-positive rates (93.2% to 96.6%) for the MA-containing case samples. In addition, their true-positive rates for the 25:75 mixtures of MA hydrochloride and diluents were within 47% to 67%. On the other hand, these spectrometers gave lower true-positive rates (76% to 88%) for the COC-containing case samples than those for the MA-containing case samples. NIRSCAN-MKII showed obviously lower true-positive rates for the 25:75 mixtures of COC hydrochloride and diluents than the other spectrometers (NIRSCAN-MKII: 10%; Target-ID: 90%; TruNarc: 52%). Moreover, all three spectrometers gave false-positives to the compounds similar to MA and α-PVP. By implementing strict criteria for positive identification, the false positives from Target-ID and NIRSCAN-MKII were prevented but consequentially allowed an increase of false negatives. This increase of false negatives by NIRSCAN-MKII was suppressed by adding the spectra of the COC hydrochloride and diluent mixtures to the spectrum library. For TruNarc, the false positives may be caused by the mixture analysis algorithm. Excluding some spectra from the spectrum library or from the target of the mixture analysis prevented identification of these compounds; however, it inhibited the false positives with minimum increase of false negatives for MA-containing and COC-containing samples. We concluded that i) without improvements, all three spectrometers had a high risk of false positives, ii) improvement of software would lower the identification range but diminish the risk of false positives, and iii) all three spectrometers were applicable to on-site screening, specifically for MA-containing and COC-containing samples after the improvement.
The present study compared decision tree analysis to logistic regression analysis in order to investigate whether decision tree analysis has sufficient ability to construct a model that predicts offender characteristics from the crime scene and/or victim information. The data used in this study were collected from solved single homicide cases that occurred in Japan between 2004 and 2009 (n=1226). After constructing models that predict offender's criminal history by logistic regression analysis and decision tree analysis, AUC (area under the ROC curve) of those models and the predictive values were compared. The AUC was .75 (p<.001) for logistic regression model and .71 (p<.001) for the decision tree model. A significant difference between these AUCs was not observed (χ2(1)=3.71, p=.05). The predictive values were 67.3% for both the logistic regression model and the decision tree model. These findings suggest that the decision tree is comparable to logistic regression analysis in constructing a model that predicts the offender's criminal history from offence characteristics in single homicide cases.
The motorcycle has a high running stability. Therefore, the motorcycle can keep running without the rider before and after a traffic accident. For Traffic accident reconstruction which involves an unmanned motorcycle, we needed the deceleration value of the motorcycle during running without a rider. Running without a rider is in much the same state as running with the engine brake on. Therefore, we investigated performance of motorcycle engine brake to use for analysis of traffic accident. Engine displacement of the motorcycles with manual transmission (MT) we used was from 250 cc to 1200 cc. And that with automatic transmission (AT) was 50 cc and 250 cc. We examined coasting tests in various speeds and various gears. In the result, we found that the motorcycle with MT speed bear a direct proportionate relationship to deceleration of engine brake running. And then, we found that speed change per unit distance doesn't depend on the motorcycle speed in case of high speed running. However, speed change per unit distance decreased in the case of low speed running by the motorcycle with MT. Simultaneously, the motorcycle with AT increased the value of speed change.
In a case that a gun shooting crime occurs, investigators are required to estimate the shot position, shot direction and the types of gun used at the scene. The lead bullets with revolvers calibered as 38SPL are used more often than metal-jacketed bullets at shooting crime scenes in Japan. The fired bullets picked up at the scenes are deformed in many cases, and sometimes fragmented, because of the collision against a structure. There is almost no report focused on the relationship between the angle of collision and the feature of lead bullet fragments. This paper gives the relationship based on the experimental result that the lead bullet collided against the steel plate or concrete block as rigid bodies. As a result, the heel of a lead bullet was fragmented by the collision against rigid body in the case that the angle of collision was more than 60°, and not fragmented in the case that the angle of collision was less than 30°.