The purpose of this study was to examine tactics that investigators in Japan regarded as effective to elicit true statements from the interviewees in investigative interviews. Six versions of a questionnaire, that were created using a combination of (a) interviewee type (three conditions: suspect, victim, or eyewitness), and (b) interviewee's attitude (two conditions: cooperative or not cooperative). Seven hundred and forty investigators were randomly given one of the questionnaires and asked to rate on a 5-point Likert scale the degree to which they should use each of 65 questionnaire items in an investigative interviewing. In the results, a factor analysis revealed five tactics: Preparation and introduction, Attentiveness, Approaching, Understanding, and Emotional. Investigators indicated that they should use Preparation and introduction, Approaching and Understanding. The pattern of results was slightly different depending on the interviewee type. Interviewee's attitude (i.e., cooperative or not cooperative) had little effect on the ratings.
Analytical results for trace elements in biological sample can provide useful information to prove that a victim had taken toxic inorganic elements. In this study, we aimed to establish a detection method to detect toxic elements in a blood stain. Simulated blood samples prepared by mixing thallium standard solution in horse hemolysis blood were dropped and dried on a filter paper. Micro X-ray fluorescence spectrometry and scanning electron microscopy/energy dispersive X-ray analysis could detect only major elements in the blood stain but not the added thallium. Laser ablation-inductively coupled plasma mass spectrometry made it possible to detect those elements in the blood stain. Calibration curve obtained by measuring filter paper made from aqueous solution or horse hemolysis blood containing thallium exhibited good linear relationship in the range of 0～500 ng/mL. The present method can be used for the qualitative screening of toxic elements in blood stains.
Methamphetamine is an illegal drug which is commonly abused in Japan. Simon and Marquis tests are used for checking the presence of methamphetamine in a sample. Recently, a new fake mixture that gives positive results for both color tests has been encountered. GC-MS measurement revealed that this mixture contained 2-phenethylamine and N-isopropylbenzylamine but not methamphetamine. We applied a color test with acetone and sodium nitroprusside which showed a positive result for 2-phenethylamine and no methamphetamine. This test along with the usual Simon and Marquis tests would be useful for the distinction of this mixture from methamphetamine.
This paper reports a new qualitative analytical approach, based on a color reaction for the detection of nitrous oxide (N2O), in order to solve problems of existing methods. The coloration was caused by the azo coupling of N2O with a Grignard reagent and 1-naphthol in the presence of CuCl2, which generated an orange-colored product 4-(phenylazo)-1-naphthol (4-PN) known as an azo dye compound. This color reaction provided both a simple color identification test and derivatization of N2O for its effective identification by gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/tandem mass spectrometry (LC/MS/MS). This approach has several advantages such as: N2O was detectable by the color identification test quickly even when it was diluted with air, the derivative 4-PN was detectable by GC/MS or LC/MS/MS using an ordinary separation column and detection limits were about 10% for the color identification test, 1% for GC/MS, and 0.01% for LC/MS/MS. Thus, this method was found to be useful for both preliminary test and confirmation of N2O in street drug samples.
Formalin-fixed paraffin-embedded (FFPE) tissues are one of the most effective tools for human identification in forensic science. To evaluate the effectiveness for human identification, we compared the following six methods for the extraction of DNA from FFPE tissues; EZ1 DNA Investigator Kit, ReliaPrep FFPE gDNA Miniprep System, DNA Isolator PS-Rapid Reagent, QIAamp DNA FFPE Tissue Kit, NucleoSpin DNA FFPE XS and phenol-chloroform method. DNA extracted using each method from two FFPE tissue blocks were quantified by three different DNA quantification methods (Quant-it dsDNA HS Assay Kit and quantitative PCR based on 207 bp and 98 bp regions in the D17Z1 locus), and short tandem repeat (STR) typing using AmpFlSTR Identifiler Plus PCR Amplification Kit was conducted. All extracts from the FFPE tissues were highly degraded, and large differences were observed among total DNA yields determined by these three quantification methods. DNA obtained using QIAamp DNA FFPE Tissue Kit had the highest total DNA yield among all the quantification methods. In STR typing with 1 ng DNA template estimated by quantitative PCR based on 98 bp region in the D17Z1 locus, the greatest number of detected alleles was observed using QIAamp DNA FFPE Tissue Kit. In contrast, EZ1 DNA Investigator Kit and DNA Isolator PS-Rapid Reagent were inferior to the other methods in terms of the DNA yield and the number of detected alleles via STR typing. In conclusion, QIAamp DNA FFPE Tissue Kit was the most effective method for human identification from FFPE tissues among the other DNA extraction methods, considering the results of this study, its cost-effectiveness, and universal use for forensic science.
Yfiler® Plus PCR Amplification Kit using a new 6-dye system detects 27 Y-STR loci. This paper describes our validation results of the Yfiler® Plus kit for forensic casework analysis. We examined sizing precision, baseline noise, sensitivity, stutter ratios, peak height ratios, spectral pull-up, the tolerance to PCR inhibitors, ability to obtain results from aged bloodstains and mixed DNA samples, and artifact peaks. In this study, electrophoresis was performed by using a 3500xL Genetic Analyzer and a 3130xl Genetic Analyzer. Data from 3500xL were analyzed with a threshold value of 175 RFU and data from 3130xl were analyzed with a threshold value of 150 RFU by using GeneMapper® ID-X software v1.4. AmpFℓSTR® Yfiler® PCR Amplification Kit was also examined in the sensitivity study, the aged bloodstains study and the inhibition study for comparison between the two Y-STR kits. In the sensitivity study, the Yfiler® Plus kit with the 3500xL generated full Y-STR profiles constantly from DNA amounts greater than or equal to 0.25 ng. Low input DNA amounts (≤0.125 ng) occasionally resulted in partial profiles. No full Y-STR profile was obtained from less than or equal to 0.031 ng DNA amounts. In the spectral pull-up study, the 3130xl showed higher spectral pull-up ratios in use of Yfiler® Plus kit than the 3500xL. In the inhibition study, in comparison with the conventional Yfiler® kit, the Yfiler® Plus kit showed higher tolerance toward hematin and humic acid. In the mixture study, full Y-STR profiles were obtained from 1 ng of male DNA mixed with 4000 ng of female DNA. Our validation studies indicate that the Yfiler® Plus kit can be used for Y-STR analysis in forensic casework.
Imaging of latent fingerprints using light sources is favorable for subsequent short tandem repeat (STR) analysis because of its fewer risks of cross-contamination. Ultra violet (UV) light is well known to be effective for fingerprint visualization. However, the degradation of DNA by two kinds of UV lamps (254 nm and 306 nm) had been previously observed. In this study, we examined the effect of the light sources for the portable imaging system on STR analysis. Twenty microliters of saliva donated from individuals #01 and #02 was dried on a glass slide, and irradiated by two kinds of halogen lamps (370-800 nm and 370-1100 nm) and by a continuous wave (CW) green laser (532 nm) for the hyperspectral imager, by a femtosecond pulsed near infrared laser (780 nm) for the two-photon excitation/ coherent anti-stokes Raman scattering (CARS) imager, and by a nanosecond pulsed near UV laser (355 nm) for the time-resolved spectroscopy. DNA was extracted from the irradiated saliva, quantified using a real-time PCR assay, and STR analysis was performed. The mean of the DNA concentration (n=4) was slightly reduced for the individual #01 by the near UV (355 nm) from 1.04±0.027 ng/μl to 0.795±0.054 ng/μl: however full STR profiles were obtained from all the samples irradiated by this UV. Light sources other than the near UV did not show significant reduction of DNA concentration under the examined conditions enough for fingerprint imaging, and full STR profiles were obtained.
In this paper, we report on the development of a forensic discrimination method for malathion formulations using the composition of organic solvents and poly (oxyethylene) surfactants contained in them. The composition of the organic solvents and the surfactants were analyzed by head-space gas chromatography mass spectrometry and matrix-assisted laser desorption ionization mass spectrometry, respectively. From examination of the solvents, 10 formulations analyzed in this study were classified into 3 groups, and from examination of the surfactants, the 10 formulations were classified into 4 groups. Finally, by combining the both results, we succeeded in classifying them into 7 groups. The result of this discrimination was consistent when those formulations were mixed with beverage samples or food samples. This method was proved to have high robustness over degradation, volatilization, or interference by matrices, which is required for the forensic discrimination of pesticide formulations.