**4. Hair analysis**

H's hair was analyzed by St. Marianna University School of Medicine, using AAS (atomic absorption spectrometry) after NaOH digestion and hydride generation technique. They found 90 ppb As3+ in her hair. The method was the same as reported in Ref. [41]. St. Marianna University knew that As3+ was not appropriately analyzed when using the method of Ref. [41], and thus they had not analyzed As3+ from 1984 to 1997 [42]. However they analyzed As3+ in 1998 in the forensic analysis of H's hairs and concluded that 90 ppb As3+ was exogenously attached to her hair. They used an old atomic absorption spectrometer, which was made in 1970s, i.e. too old, using paper and a pen-recorder, and measured the peak height with a rule. In early 1990s, the chemical state analysis of arsenic had been performed by an ion chroma‐ tography (IC)/ICP-MS or an HPLC/MS [43] and the analytical instruments had been compu‐ terized. The advancements of these analytical instruments were due to the zenith of the semiconductor industry [44]. Therefore St. Marianna University obtained As3+ concentration using an old non-computerized AAS machine, where chemical state of arsenic compounds changed depending on pH. Therefore the forensic analysis results on the chemical state of arsenic of H's hairs were quite doubtful.

Many of H's hairs were also measured at BL-4A of KEK-PF (Photon Factory at High Energy Accelerator Research Organization, a synchrotron radiation facility in Tsukuba), and found an arsenic particle on a hair. The synchrotron radiation beam size was 4 or 1 mm width along with the hair shaft. It is still not clear how many hair shafts were measured and how many particles were found. It is said that arsenic particle was found on only one or two hair shaft(s), using 100 h of the KEK-PF beam time for hundreds of hair shafts.

At SPring-8, the same hair was measured but arsenic signal was not detected and testified that the spectral data was deleted [44].

**Figure 5.** Photo of measuring the paper cup (1) at the beamline BL-4A of KEK-PF, taken from the legal document of the Tokyo University of Science [39]. The document is a public document, not a copyrighted matter.

At KEK-PF, the paper cup (1) was measured, where arsenic powder was adsorbed on the surface of the cup (**Figure 5**). The hair shafts were measured at the same measurement chamber at the same beam time using a holder shown in **Figure 6** [45]. The hair and the paper cup were handled carelessly and cross-contamination might have been happened. The detection limit of arsenic at KEK-PF was worse than 90 ppb, and thus the SR-XRF analysis results contradicted with the AAS results.

**Figure 6.** Photo of hair shaft holder used at BL-4A of KEK-PF, taken from the grant report document of the Tokyo Uni‐ versity of Science [45]. The document is a public document, not a copyrighted matter.

It should be pointed out that scanning electron microscope energy dispersive X-ray analysis (SEM–EDX) was not used for the hair analysis. SEM–EDX was much easier and direct observation method compared with the SR-XRF line scan. Uranium particle attached to a hair shaft was clearly observed using an SEM–EDX rather than SR-XRF, which was reported in 2015 [46], but this type of SEM–EDX analysis was possible even in 1998. It is quite strange why such a direct observation using an SEM–EDX had not been performed in 1998.
