REVISIT OF FORENSIC ANALYSIS OF ARSENIC POISONING CASE 1998

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1 Copyright JCPDS-International Centre for Diffraction Data 2014 ISSN REVISIT OF FORENSIC ANALYSIS OF ARSENIC POISONING CASE 1998 Jun Kawai Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto , Japan ABSTRACT High energy synchrotron radiation X-ray fluorescence (SR-XRF) spectra for the forensic analysis of Wakayama arsenic poisoning case, Japan, were revisited. The spectra were measured at SPring-8 synchrotron facility by Nakai in December 1998 and Mo, Sn, Sb, and Bi were used as index elements at that time to demonstrate that the suspected saleswoman s pesticide and that found near the curry pot were the same. The pesticide was identical with respect to Mo, Sn, Sb, and Bi, because these impurity elements were originated from the smelting process of arsenic ore. Based on the analysis of Mo, Sn, Sb, and Bi XRF peaks, the suspect was sentenced to death without her confession. In the present paper, the importance of bench-top XRF spectrometer analysis (Si and Ca) as well as the importance of the ordinary X-ray diffraction are pointed out for identification, which were neglected in the court. INTRODUCTION The Wakayama arsenic poisoning case in Japan involved a curry pot that was poisoned by arsenic trioxide, As 2 O 3, during a summer festival in Wakayama city in This resulted in the deaths of four people and an additional 60 people who became sick (Kawai 2014). Evidence was analyzed at SPring-8, the third generation synchrotron radiation facility. The identification by pattern recognition of the X-ray fluorescence spectra using impurity elements (Sn, Sb, Mo, and Bi) found in arsenic oxide powder adhered in the paper cup found near the curry pot and arsenic oxide particles attached to a plastic box found in the kitchen of the suspected insurance saleswoman was key

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3 Copyright JCPDS-International Centre for Diffraction Data 2014 ISSN evidence for the death penalty. The saleswoman who is now in death row has always denied the poisoning. The purpose of the present paper is to show that only the synchrotron radiation X-ray fluorescence (SR-XRF) analysis is not enough for the complete forensic analysis. By using spectra measured by a bench-top XRF spectrometer and X-ray diffraction (XRD) patterns other than SR-XRF, we can now know more truth than was known by SR-XRF data at that time. RE-ANALYSIS OF X-RAY DATA SUBMITTED TO COURT The arsenic was used at Wakayama city as white ant pesticide. Pure arsenic oxide (As > 76 wt%) was imported from China in a green 50-kg can, and arsenic oxide powder was distributed from this single can. It was known before the SR-XRF analysis, that Bi (57+6 ppm), Pb (198+4 ppm), Sb (27+1 ppm), Sn (23+3 ppm), and Se (99+19 ppm) were contained as impurity elements in the arsenic oxide in the 50-kg can, analyzed by ICP-AES (Marumo et al. 1998). The typical weight concentration of each impurity elements is indicated by parentheses above. The elemental arsenic concentration in the 50-kg can was known to be % by ICP-AES (Marumo et al. 1998) and thus the arsenic in the can was almost pure, because As/As 2 O 3 =75.8 wt%. When this arsenic was used as pesticide, some people mixed cement, some mixed starch, and some mixed both. The police found several arsenic oxide powders around the suspected saleswoman s house. Mr. M. had stored the arsenic oxide in a green 50-kg can (Specimen #1), in a milk can (Specimen #2), in a metal can indicated as heavy (because arsenic oxide is relatively high density, and thus heavy; Specimen #3), and in a plastic box (Specimen #4); Mr. T., who lived in the suspected saleswoman s old house when the murder case happened, had arsenic oxide in a milk can (Specimen #5), which was left when the saleswoman moved to a new house; the suspected saleswoman stored arsenic oxide in a plastic box in her kitchen (Specimen #6); arsenic oxide powder (more than 30 mg) adsorbed to a paper cup (Specimen #7) was found near the curry pot. Though arsenic oxide crystals were also found in the curry pot, analysis of these curry pot crystals is not treated in the present paper.

4 Copyright JCPDS-International Centre for Diffraction Data 2014 ISSN Figure 1. A typical SR-XRF spectrum measured by Nakai (1999) for Specimen #4. Two peaks between 30 and 40 kev are Ba K and K. Figure 1 shows a typical SR-XRF spectrum of Specimen #4 measured by Nakai (1999). Characteristic X-ray peaks of As, Mo, Sn, Sb, and Bi are found, though the plotting is relatively not clear below 20 kev. The peaks over 70 kev which are not assigned, are those of Pb, which was due to the X-ray collimator in the beamline. The peaks between 30 and 40 kev, not assigned, are Ba K and K. Specimen #1 - #7 exhibited quite similar patterns with respect to the peaks of Mo, Sn, Sb, and Bi, while arsenic not originated from the 50-kg green can lacked some of these impurity peaks. Thus Specimen #1 - #7 were concluded to be the same origin (50-kg green can) by the SR-XRF analysis by Nakai (1999), which had already been known by testimony except for Specimens #6 and #7, before the SR-XRF analysis. However, since the procedure of the SR-XRF was too complicated for lawyers, prosecutors, and the judge, some misunderstood that Specimens #6 and #7 were exclusively identical. This is because the SR-XRF was very expensive and sensitive, and such analysis would have clarified a fingerprint-like elemental pattern only existing between Specimens #6 and #7, from the description of the one-thousand-page length death sentence document written by the judge. The reason why the index elements in Figure 1 (Mo, Sn, Sb, and Bi) were present in the arsenic was not understood by the lawyers, prosecutors, and the judge. These impurity elements were known that came from the smelting process, and were

5 Copyright JCPDS-International Centre for Diffraction Data 2014 ISSN thus related to the origin of the arsenic, i.e., the 50-kg green can. It had already been known by the testimony of the neighbors that Specimens #2-#5 were came from #1. This was also supported by the ICP-AES analysis, except for Specimen #6 (Specimen #6 was not found at that time) (Marumo et al. 1998), from the concentration pattern of Se, Sn, Sb, Pb, and Bi before the SR-XRF analysis. Some in the court misunderstood that the SR-XRF gave information further than the testimony. That is to say, the SR-XRF analysis was misunderstood that the Specimen #7 (paper cup) was identical to solely Specimen #6 (saleswoman s kitchen), and that Specimen #7 was not identical to other arsenic oxide including Specimens #1-#5. Based on these misunderstandings, the death penalty was decided. Table 1. Ba peak presence (+) or absence (-) analyzed by SPring-8 SR-XRF in 1999 and Specimen # Nakai Taniguchi and Hayakawa The presence or absence of barium in Specimens #1-#7, as determined by Nakai (SR-XRF) and Taniguchi and Hayakawa (also SR-XRF) is shown in Table 1. Barium was known to be an impurity element of cement-like powders mixed into the arsenic pesticide. The difference between 1999 and 2002 results indicates that cement was not homogeneously mixed. Though the presence or absence of barium in the key Specimens #5, #6, and #7 were inverted between two analyses, we can conclude that Specimens #3-#7 and curry pot all contained barium. On the contrary, Specimen #1 and #2 did not contain barium. This is quite natural that Specimens #1 and #2 were pure arsenic oxide imported from China by a green can, but #3-#5 were known to be mixed with cement-like material from the testimony of the neighbors. The concentration of barium was ranging from 2 to 36 ppm (SR-XRF, Taniguchi and Hayakawa 2002). Though the presence of barium supported the identity of Specimens #6 and #7, as is discussed below, the chemical state of barium was different among Specimen #3, #4, and #5, and thus which chemical state, or which of Si and/or Ca was mixed is an important issue to identify Specimens #6 and #7. However low energy light element peaks such as Si and Ca were not detected by the SR-XRF analysis because only a 115 kev incident X-ray beam was used for excitation.

6 Copyright JCPDS-International Centre for Diffraction Data 2014 ISSN Figure 2. SII-SAE 5120 bench-top XRF spectra of Specimen #3 (top left), #4 (top right), and #5 (bottom), taken from Taniguchi and Hayakawa (2002). Figure 2 shows XRF spectra measured by an SII SAE 5120 bench-top XRF spectrometer with Mo target X-ray tube (Taniguchi and Hayakawa 2002). It is found from the spectra in Figure 2 that Specimen #3 contains Ca, Specimen #4 contains Si, and Specimen #5 contains both Si and Ca. Based on the spectra shown in Figure 2, Ba was originated from Ca impurity or Si impurity. Calcium and silicon were so-called cement-like materials by the testimony of the neighbor people.

7 Copyright JCPDS-International Centre for Diffraction Data 2014 ISSN Figure 3. X-ray diffraction data of residue of Specimen #4. Top: Measured XRD, bottom upper half: extracted data from measured XRD, bottom lower half: SiO 2 reference XRD pattern, taken from Taniguchi and Hayakawa (2002). Taniguchi and Hayakawa (2002) dissolved Specimens #4 (Si detected) and #5 (both Si and Ca detected) into HCl+HNO 3 acid and the non-dissolved residue was measured by XRD (Figure 3) and SR-XRF (Figure 9 in Kawai 2014, though explanation of Figure 9 was omitted in Kawai 2014). Figure 3 shows an XRD pattern of residue of Specimen #4, once dissolved into acid. Barium in Specimens #3 and #5 was an impurity of calcium from the experiment of dissolving into the mixed acid. It is concluded from XRD that cement-like material which contained barium in Specimen #4 was SiO 2, not calcium in cement. In summary, Taniguchi and Hayakawa (2002) concluded that barium in Specimens #4 and #5 was different in chemical state. Barium in Specimen #4 existed in non-dissolved component to acid, and thus it was included in SiO 2. On the other hand, barium in Specimens #3 and #5 was included in the acid-dissolved component, and thus barium was an impurity in calcium compounds. These conclusions were supported by the results of SR-XRF analysis of non-dissolved residues (Taniguchi and Hayakawa 2002). In the court, these analyses were all overlooked and only the SR-XRF pattern of Mo, Sn, Sb, and Bi, was used. The concentration of arsenic in the paper cup was 74.8 wt%, which was the result of ICP-AES (Marumo et al. 1998). Since the arsenic in arsenic trioxide is 75.8 wt% as mentioned above, the impurity was less than 2 % in the paper cup. The saleswoman s plastic box in the kitchen (Specimen #6) was heavily mixed by cement because of the

8 Copyright JCPDS-International Centre for Diffraction Data 2014 ISSN presence of barium peak (Figure 1 in Kawai 2014). Therefore not only by the pattern of the impurity elements (Mo, Sn, Sb, and Bi), but also concentrations of other impurity elements such as Ba, Ca, and Si are important parameters to identify the evidences. The prosecutor thought that the suspected saleswoman brought a part of arsenic from her old house (Specimen #5) to the kitchen of her new house (Specimen #6), then she poisoned the arsenic into the curry pot by the paper cup (Specimen #7). However, from the ICP-AES results of Marumo et al. (1998), As concentration was 49 wt% for Specimen #5, but it was75 wt% for Specimen #7. Specimen #6 was too small amount to determine the As concentration by the ICP-AES. Thus SPring-8 was used for impurity analysis. However Specimen #6 shows not weak intensity of Ba K from the analysis of Nakai (1999). This fact suggests that Specimen #6 was heavily mixed with cement-like material. The paper cup (Specimen #7) also contains barium, but the arsenic concentration was as high as pure arsenic oxide. This is quite strange. CONCLUSIONS Third generation synchrotron radiation high energy (115 kev) incident X-ray fluorescence (SR-XRF) analysis was used for the forensic analysis of arsenic poisoning murder case in Japan. The analysis of elements such as Si and Ca could be an important index to identify materials that were used to dilute the pesticide, which was completely neglected in the court. If these elements were analyzed, there is a possibility that the results would demonstrate that the person in the death row is innocent. We must use as many analytical methods as possible to evaluate the evidence, even the third generation synchrotron facility for which the X-ray beam is billions of times stronger than the sun light. REFERENCES Y. Marumo, Y., Suzuki, S., and Ohta, H. (1998). Legal advice document, Prosecution #1168, 15 December Nakai, I. (1999). Legal advice document, Prosecution #1170, 19 February Taniguchi, K., and Hayakawa, S. (2002). Legal advice document, Court Order #6, 5 November 2002.

9 Copyright JCPDS-International Centre for Diffraction Data 2014 ISSN Kawai, J. (2014). Forensic analysis of arsenic poisoning in Japan by synchrotron radiation X-ray fluorescence, X-Ray Spectrom., 43, 2-12, DOI /xrs.2462.