Salvation of a Saint

TWENTY-SEVEN

Yukawa used a spoon to scoop coffee into the paper filter.

‘I see you’ve got used to your coffeemaker,’ Utsumi commented from behind him.

‘Got used to it, yes – but at the same time I’ve become aware of a shortcoming.’

‘Oh? What’s that?’

‘You have to decide how many cups you want to make up front. Of course, once you realize that two or three won’t be enough, you can always make more. But it’s a pain to go to all that trouble for just one extra cup. Which means I find myself making enough for an extra cup but then I risk making too much. I hate to throw out perfectly good coffee, and if I leave it on the burner too long, the flavour changes. You see?’

‘Well, you won’t have to worry about that today. I’ll drink whatever’s left over.’

‘Oh, we’re fine today. I’ve only made four cups. One for you, one for me, and one for Kusanagi. The final cup I’ll drink at my leisure after you’ve left.’

Clearly, the physicist wasn’t planning on keeping them long. Utsumi had her doubts that things would go so smoothly. Unless Yukawa’s going to stop being coy and solve the puzzle once and for all.

‘You know, the entire department is grateful to you, Professor,’ she said. ‘If you hadn’t insisted on it, we never would have taken the extra step of sending the filtration system on to Spring-8’s lab.’

‘There’s no particular need to thank me. I merely gave the advice that any scientist would in that situation.’ Yukawa sat down across from the detective. There was a chessboard on the workstation between them; he picked up the white knight and began toying with it. ‘So they found the arsenous acid.’

‘We had them run a full analysis. The acid in the filtration system was almost certainly that used to kill Yoshitaka Mashiba.’

Yukawa nodded, returning the piece to the chessboard. ‘Did they say in which part of the system they found the poison?’

‘It was near the water outlet, not in the filter itself. Forensics thinks the killer inserted the poison into the joint that connects the filtration system with the water hose running up from the main line.’

‘I see.’

‘The only problem,’ Utsumi continued, ‘is that they can’t figure out how the killer did it. So how was it done? We’ve got the results from Spring-8 you wanted. Surely you can reveal the trick now.’

Yukawa rolled up the sleeves of his white lab coat and crossed his arms. ‘Forensics couldn’t figure it out?’

‘They say there’s only one possible method: you would have to remove the hose from the filtration system, put the poison in, then reattach it. But that would leave certain telltale signs – marks on the hose or whatever – which they didn’t find.’

‘And you have to know exactly how it was done?’

‘Of course. If we can’t prove how the crime was committed, it doesn’t matter if we have a suspect.’

‘Even though you found the poison?’

‘We won’t have a chance in court if we don’t know how the crime was committed. The defence will claim police error.’

‘Oh?’

‘They’ll say that there’s a possibility that some of the arsenous acid in the coffee made its way to the filtration system after the fact. We are talking about trace molecules here.’

Yukawa sat back in his chair, nodding his head slowly. ‘They might make that argument, it’s true. And if the prosecution couldn’t provide a means of insertion, the court would have to listen to the defence.’

‘Which is why we really need you to explain how it was done. Please. Forensics wants to know, too. Some of them even wanted to come with me to hear it from you firsthand.’

‘Well, that won’t do. I can’t have police tromping through my lab.’

‘Which is why I came by myself. Well, and Detective Kusanagi’s coming later on.’

‘Speaking of which, shouldn’t we wait for him to get here? I don’t want to have to repeat my explanation. Also, there’s one last thing I need to check first.’ Yukawa lifted an index finger. ‘In your department’s opinion – no, actually, your personal opinion is fine – what was the motive for the murder of Yoshitaka Mashiba?’

‘Well, I think romantic troubles would pretty much sum it up.’

Yukawa frowned. ‘Isn’t that a rather abstract motive on which to rest your case? Try telling me who loved whom, who hated the victim enough to kill him, and why.’

‘Well, it’s all conjecture at this point …’

‘Fine. Like I said, all I’m looking for is your personal opinion.’

Utsumi nodded; she lowered her eyes, collecting her thoughts.

Steam bubbled from the coffeemaker. Yukawa stood and retrieved two coffee mugs from the sink.

‘Well,’ Utsumi said as he began to pour the coffee, ‘I think Ayane Mashiba did it. Her motive was that she felt her husband had betrayed her – not just because he asked her for a divorce when he decided she couldn’t bear him children, but also because he had started seeing another woman. That’s what pushed her to murder.’

‘Do you think she made up her mind the night of the party at the Mashiba house?’ Yukawa asked.

‘She probably made her final decision that night, yes. But I think it’s likely she had started harbouring murderous intentions a little earlier than that. She knew about Yoshitaka and Hiromi Wakayama. She also had intimations of Hiromi’s pregnancy. Yoshitaka’s declaration was the final straw.’

Yukawa returned to the table, holding a coffee cup in each hand. He placed one in front of Utsumi. ‘What about this woman, Junko Tsukui? Did she have nothing to do with the murder, then? Isn’t Kusanagi out there right now questioning people about that?’

The likelihood of a personal connection between Junko Tsukui and Ayane Mashiba was the first thing Utsumi had mentioned to Yukawa when she got to the lab.

‘I wouldn’t say there’s no connection. It’s likely that the arsenous acid used in this murder was the same that Ms Tsukui used to kill herself. If Ayane was close to her, she would’ve had an opportunity to get the poison from her.’

Yukawa raised his cup and his eyebrow at Utsumi. ‘And then?’

‘Excuse me?’

‘Is that all Junko Tsukui had to do with it? She just provided the poison? Her death doesn’t factor into the motive at all?’

‘Well, it’s hard to say …’

Yukawa smiled thinly and sipped his coffee. ‘Then it’s hard for me to tell you the trick.’

‘What?! Why?’

‘Because telling you would be far too dangerous. You haven’t yet figured out what this case is really about.’

‘And you have?’

‘More precisely than you.’

Utsumi was glaring at Yukawa, both hands clenched around her mug, when they heard a knock at the door.

‘Good timing! Maybe Kusanagi can shed a little light on the subject,’ the professor said, rising to his feet.