Ritsuko Sugita

Validity of color examination for forensic soil identification

The validity of a multiple measurement procedure for forensic soil identification was studied using 73 soil samples from an area where volcanic ash soils, alluvial soils and residual soils dominate. Soil color was measured by comparison to Munsell color charts after each of several treatments: (1) air-drying, (2) moistening, (3) organic matter decomposition, (4) iron oxide removal, and (5) ashing. In addition, the colors of the clay fractions were observed after organic matter decomposition and after iron oxide removal. Although only about 70% of soils could be differentiated by comparing the colors of air-dried samples, combining color measurements on soils after air-drying and moistening, and on the clay fraction after organic matter decomposition and iron oxide removal enabled us to differentiate 97% of soil samples. Adding color measurements of ashed soil to the above procedure did not provide any further improvement in the discriminatory power of the multiple color measurement.

Screening of soil evidence by a combination of simple techniques: validity of particle size distribution

The validity of the determination of particle size distribution for forensic soil identification was studied using 73 soil samples collected from a 20 km x 15 km area. Soil particles were first divided into two fractions by wet sieving with a sieve with a 0.05 mm aperture size. Dry sieving was used to analyze the coarse particle fraction and a particle size analyzer was used for the fine particle fraction. The number of particle size classes measured by sieving could be reduced to three, <0.05, 0.05-0.2, and 0.2-2 mm, which enabled 87.9% of the soil samples to be discriminated. Measurements made with the particle size analyzer on the fine particle fraction increased the discriminating power to 95.9%. The use of particle size analysis by sieving in combination with color examination allowed us to discriminate 99.5% of the soil samples, even when particle size analysis of the fine particle fraction was not carried out.

Microspectrophotometric discrimination of single fibres dyed by indigo and its derivatives using ultraviolet-visible transmittance spectra

Single fibres dyed by indigo and its seven derivatives were measured by microspectrophotometric examination of transmittance spectra in the ultraviolet-visible region (240-760 nm). Glycerin was the most suitable embedding reagent for this measurement. Small intra-sample variation of the transmittance intensity in single woollen fibres was observed, but relatively large inter-sample variation was observed among the fibres obtained from different areas in the same textile. There were no differences in the hmax, hmin and the position of shoulders observed in their spectra. This method was applied to the discrimination of single cotton fibres dyed by vat dyes, such as indigo and seven indigo derivatives which had similar structures. On the basis of the ultraviolet-visible transmittance spectra, these sample fibres could be distinguished from one another. It is a non-destructive method compared with chromatographic dyestuff extraction methods; furthermore, utilization of the ultraviolet region gave spectra providing useful information for evaluating fibre evidence.

Illegal Route Estimation of the Seized Illicit Drug, Methamphetamine, by the Comparison of Striation Marks on Plastic Packaging Films

Abstract:  In Japan, the most common illicit drug is methamphetamine. It is possible to trace the origin of this drug by analyzing its organic and inorganic impurities and/or byproducts using several methods, such as GC, GC/MS, and inductively coupled plasma‐mass spectrometry (ICP‐MS). As reported here, one other method includes comparison of the striation lines of polymer sheet layers from packaging using a polarized light method. Other alternative methods include analyzing the heat sealer pattern, layer thickness surface characteristics, and/or components of polymer sheet layers using infrared spectroscopy. Several of these alternative methods were used to analyze the origins of 29 packages confiscated from three regions over a 1000 km distance in Japan. Results indicated that packages seized from different regions had some polymer sheet layers which contained striation lines and heat sealer patterns that were similar.

Guilty by his fibers: suspect confession versus textile fibers reconstructed simulation

In one particular criminal case involving murder and theft, the arrested suspect admitted to the theft, but denied responsibility for the murder of the inhabitant of the crime scene. In his confession, the suspect stated that he found the victims body when he broke into the crime scene to commit theft. For this report, the actual crime scene was reconstructed in accordance with the confession obtained during the interrogation of the suspect, and suspect behavior was simulated in accord to the suspect confession. The number of characteristic fibers retrieved from the simulated crime scene was compared with those of retrieved from the actual crime scene. By comparing the distribution and number of characteristic fibers collected in the simulation experiments and the actual investigation, the reliability of the suspects confession was evaluated. The characteristic dark yellowish-green woolen fibers of the garment that the suspect wore when he entered the crime scene were selected as the target fiber in the reconstruction. The experimental simulations were conducted four times. The distributed target fibers were retrieved using the same type of adhesive tape and the same protocol by the same police officers who conducted the retrieval of the fibers at the actual crime scene. The fibers were identified both through morphological observation and by color comparisons of their ultaviolet-visible transmittance spectra measured with a microspectrophotometer. The fibers collected with the adhesive tape were counted for each area to compare with those collected in the actual crime scene investigation. The numbers of fibers found at each area of the body, mattress and blankets were compared between the simulated experiments and the actual investigation, and a significant difference was found. In particular, the numbers of fibers found near the victims head were significantly different. As a result, the suspects confession was not considered to be reliable, as a stronger contact with the victim was demonstrated by our simulations. During the control trial, traditional forensic traces like DNA or fingerprints were mute regarding the suspects says. At the opposite, the fiber intelligence was highly significant to explain the suspects behavior at the crime scene. The fiber results and simulations were presented at the court and the man was subsequently found guilty not only of theft and trespassing but also murder.

Forensic Discrimination of Match Heads by Elemental Analysis with Inductively Coupled Plasma-Atomic Emission Spectrometry

In arson and bombing cases, matches are often used as the ignition method. We have investigated the use of elemental analysis by inductively coupled plasma-atomic emission spectrometry to discriminate match heads used in arson cases. Six elements, magnesium, aluminum, calcium, iron, zinc, and barium, in match heads were detected after the match heads were dissolved in HNO3, and these elements were quantified in 8 wood stick matches and 5 paper stick matches by means of calibration curves prepared from standard sample solutions. Using this method, we were able to distinguish all the matches from one another both before and after combustion. The method has the potential to be very useful for resolving arson cases.

Species identification of white false hellebore (Veratrum album subsp. oxysepalum) using real-time PCR

Food poisoning is frequently caused by the accidental ingestion of toxic plants that possess strong morphological similarities to edible plants. False helleborine (Veratrum album) is one of the most common plants involved in such accidents. In cases of poisoning by toxic plants, rapid and accurate identification, usually based on the morphological or chemical analysis of plant parts, is required for appropriate medical treatment or forensic investigation. However, morphological examinations require experience in systematic botany because the samples are fragmentary, and chemical analysis of natural compounds can be difficult. In this study, we developed a TaqMan real-time PCR method using trnH-psbA and trnL-trnF that could be carried out in 30-60min. The lower detection limit was less than 10pg of DNA and the primer sets were specific to V. album and Veratrum stamineum. Mixed samples, cooked samples, and simulated gastric contents were successfully identified, and a multiplex assay of two regions was also possible. These results indicate that the TaqMan real-time PCR analysis is a very effective method to detect small samples of V. album and V. stamineum accurately and rapidly in poisoning cases.

Real-Time PCR Quantification of Chloroplast DNA Supports DNA Barcoding of Plant Species

Species identification from extracted DNA is sometimes needed for botanical samples. DNA quantification is required for an accurate and effective examination. If a quantitative assay provides unreliable estimates, a higher quantity of DNA than the estimated amount may be used in additional analyses to avoid failure to analyze samples from which extracting DNA is difficult. Compared with conventional methods, real-time quantitative PCR (qPCR) requires a low amount of DNA and enables quantification of dilute DNA solutions accurately. The aim of this study was to develop a qPCR assay for quantification of chloroplast DNA from taxonomically diverse plant species. An absolute quantification method was developed using primers targeting the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene using SYBR Green I-based qPCR. The calibration curve was generated using the PCR amplicon as the template. DNA extracts from representatives of 13 plant families common in Japan. This demonstrates that qPCR analysis is an effective method for quantification of DNA from plant samples. The results of qPCR assist in the decision-making will determine the success or failure of DNA analysis, indicating the possibility of optimization of the procedure for downstream reactions.

Forensic DNA Analysis of Wheat Flour as Commonly Used in White Powder Cases.

In the wake of terrorist attacks using anthrax and ricin, white powder is often encountered in cases of malicious mischief and terrorist threats. Wheat flour is a common white powder encountered in such criminal investigations. We used DNA analysis to investigate wheat flour samples for identification and discrimination as trace evidence. Species identification of commercially available wheat flour was carried out by sequencing a partial region of the ribulose bisphosphate carboxylase large subunit gene (rbcL). Samples were discriminated using short tandem repeat (STR) analysis. The rbcL sequences of all wheat flour samples were identical and showed a high level of similarity to known wheat (Triticum aestivum L.) sequences. Furthermore, flours had characteristic patterns in STR analyses, with specific cultivars showing distinctive patterns. These results suggested that the identification of wheat flour species is possible using rbcL sequencing, and that STR analysis is useful for discriminating between samples.

Effects of printing and ninhydrin treatment on forensic analysis of paper

Paper is ubiquitous in human activities and can be found as evidence in the commission of many crimes such as threatening letters, deceptive advertisements and counterfeiting banknotes. To link the paper evidence to a source is a comparative process that is hampered when a blank paper is compared to a paper that has been submitted to printing or other treatments such as ninhydrin for the detection of fingermarks. During a forensic investigation, printed paper is analyzed with various instruments after fingerprint examination. In this study, the effects of printing and ninhydrin treatment on forensic paper examination of grammage, thickness, fillers, and pulp composition were studied. Grammage and thickness were increased by full-page double-sided printing, and grammage depended on the type of printer. The effects of printing on the analytical data about fillers and pulp composition were negligible, and ninhydrin treatment affected only paper thickness. These minor effects notwithstanding, the results indicate that conventional analytical methods used in forensic science for examining papers can be applied.