Kusanagi shook his head, muttering, ‘no way,’ over and over. But as the argument sank in, his denials gradually lost their strength.
He remembered something Ikai had said about Ayane’s peculiar devotion to her husband.
‘She was the perfect wife, you know. Utterly dedicated to him. Whenever he was home, she would sit there on the living room sofa, doing her patchwork, ready to serve if he needed anything.’
His thoughts travelled back to his visit with Ayane’s parents at their home in Hokkaido. Hadn’t they told him that she had never been a good cook, until those classes she took right before getting married?
In both cases, she was just making sure that no one else would ever enter the kitchen.
‘So when she finally wanted to kill him … she didn’t have to do anything,’ Utsumi said.
‘That’s right. Nothing at all. All she had to do was leave her husband alone in the house. Actually, that’s not quite true; there was one thing. She emptied a few of the bottles of mineral water first, leaving only one or two behind. As long as Yoshitaka was drinking those, nothing would happen. He probably used the bottled water the first time he made coffee. But when he made it for himself the second time, he was down to one bottle, and since he wanted to save that for later, he used water from the filter. After sitting in place for a whole year, the poison finally had its chance to do its job.’
Yukawa picked up his coffee mug from the table. ‘She could have killed him at any point over the last year, but she didn’t. Instead she watched carefully over her trap to make sure he never poisoned himself by accident. Most killers worry about how they’ll do the deed, but in this case, it was the complete opposite. All of her efforts went towards not killing him. It was a very unusual kind of murder, you have to admit. While it is theoretically possible, it’s entirely unrealistic. An imaginary solution, if you will.’
Utsumi took a step towards Kusanagi. ‘We have to go and confront Mrs Mashiba and get her to turn herself in.’
Kusanagi took one look at the victorious expression on the junior detective’s face before turning his gaze to Yukawa. ‘Is there proof? Is there any way to show what she did in court?’
The physicist took off his glasses, resting them on the table beside him. ‘Of course there’s no proof,’ he said.
Utsumi looked at him in surprise. ‘Really?’
‘Give it a moment’s thought and you’ll see. If she had done something, she might’ve left a trace. But she killed him by doing nothing. Look all you want for some trace of what she did, and you won’t find a thing. About the only thing you have to go on is the poison they found in the filter, but you told me yourself that evidence is inconclusive. And the detail about the part number on the filter is circumstantial at best. In other words, there’s no way at all to prove she killed her husband.’
‘I don’t …’ Utsumi’s protest trailed away into silence.
‘Didn’t I tell you before?’ Yukawa’s face was grim. ‘It’s the perfect crime.’
TWENTY-NINE
Utsumi was going through paperwork at the Meguro station when Mamiya came in from outside and shot her a look. She stood and went over to his desk.
‘I was just talking to the section chief about that case,’ Mamiya said, sitting down. He had a glum look on his face.
‘Did we get a warrant?’
Mamiya gave her a shake of his head. ‘No, we didn’t, and we won’t unless there’s some significant development. We don’t have enough material to identify our killer. I’m impressed as always with Galileo’s detective work, but without proof, we can’t go to trial.’
‘That’s what I was afraid of,’ Utsumi said, her head hanging. This was playing out just as Yukawa said it would.
‘Everyone in administration is pulling their hair out. Who the hell arranges everything for someone to poison themselves, then watches carefully for a year to keep them from doing it? No one believed me at first. Not even I believed me at first. It’s clearly the only answer here, but that doesn’t make it any easier to swallow. It just sounds so … impossible.’
‘I didn’t believe it myself when Professor Yukawa first laid it out.’
‘There’s no accounting for what some people are capable of, clearly. That goes for this woman, Ayane, as well as the professor. You have to wonder what’s going on in those heads of theirs, sometimes,’ Mamiya said, a bitter look on his face. ‘We still don’t even know if he was actually right. And as long as we can’t say for sure, we can’t touch Ayane Mashiba.’
‘What about the Junko Tsukui angle? I hear Forensics checked out her mother’s house in Hiroshima?’
Mamiya nodded. ‘They sent that can that had the arsenous acid in it down to Spring-8. The problem is, even if they do find traces, and those happen to match the arsenous acid used in this case, it’s still not conclusive evidence. It may not even be circumstantial evidence. After all, if Junko Tsukui was Yoshitaka Mashiba’s former lover, it could’ve been him carting around the poison all that time.’
Utsumi breathed a deep sigh. ‘So how do we get proof? Tell me what we need and I’ll find it. I don’t care what it takes! I can’t believe that Yukawa’s right and that this is the perfect crime!’
Mamiya’s face twisted into a scowl. ‘Don’t start barking at me,’ he said. ‘Believe me, if I knew how to get proof, we wouldn’t be in this mess. About the only evidence we have worth anything right now is that water filter with the traces of arsenous acid in it. Section thinks we need to focus on that and get everything out of it we can.’
Utsumi bit her lip. What the chief was saying sounded suspiciously like an admission of defeat.
‘Don’t give me that face, I haven’t given up yet. We’ll find something. It’s not easy to pull off the perfect crime.’
Utsumi nodded in silence, bowed, and left. You’re right, she thought, it’s not easy. But what Ayane Mashiba did would have been nearly impossible for an average person. What if that’s all it takes? What if she pulled it off?
Back at her desk, Utsumi pulled out her mobile and checked voice mail, hoping that Kusanagi had found something, but the only message was from her mum.
THIRTY
Hiromi Wakayama was already there when Kusanagi arrived at the café. He hurried over to the table.
‘Sorry to keep you waiting.’
‘I just got here myself,’ she told him.
‘Well, thanks for coming out. I’ll keep this as short as possible.’
‘Don’t worry on my account,’ Hiromi told him with a soft chuckle. ‘I’m not working right now, so I have plenty of time.’
Her complexion seems to have improved, Kusanagi thought. Back up on her emotional feet, maybe.
A waitress came to hover by their table, so Kusanagi ordered coffee. ‘Milk for you?’ he asked Hiromi.
‘Lemon tea, please,’ she said.
The waitress left and Kusanagi smiled. ‘Sorry. I just remembered you ordering milk last time …’
‘Actually, I’m not really a big fan of milk. And I’m trying to avoid it right now.’
‘Really? Why is that?’
Hiromi lifted an eyebrow. ‘Do I need to answer every question?’
‘No.’ Kusanagi waved his hand. ‘Of course not. Sorry, I was just making small talk. I’ll get down to business. The real question I have for you is about the Mashibas’ kitchen, actually. Do you remember that they had a water filter attachment on their sink?’
‘Sure.’
‘Did you ever use it?’
‘Never,’ Hiromi said without a moment’s hesitation.
‘That was quick,’ Kusanagi observed. ‘I mean, that’s the sort of question people usually have to think about a bit.’
She shook her head. ‘I barely even went into their kitchen. I never helped cook. Why would I touch the sink? I think I told detective Utsumi this, too, but the only time I ever went into the kitchen was to put on coffee or tea when Ayane asked me to, and that was only when she was in the middle of preparing someth
ing else and didn’t have time.’
‘So, is it true then that you were never in the kitchen alone?’
Hiromi frowned. ‘I’m not really sure what you’re getting at.’
‘I just need to know if you were ever in the kitchen by yourself. Don’t worry about why. Try to remember for me.’
Hiromi thought about it until wrinkles formed across her brow. Eventually she looked back up at Kusanagi. ‘Maybe not. I always had the feeling I wasn’t welcome in there without Ayane’s permission.’
‘Did she specifically tell you not to go in without permission?’
‘Not in so many words, no. It was just a feeling I had. And – you know, the whole thing about a housewife’s kitchen being her castle.’
‘So they say.’
The drinks arrived. Hiromi squeezed her lemon wedge over her tea and sipped at it, a smile on her face. She looked more alive than Kusanagi had ever seen her.
Certainly more alive than I feel. Everything she was telling him backed up Yukawa’s story.
He took a sip of his coffee and rose from the table. ‘Thanks again for your help.’
Hiromi’s eyes went wide. ‘That’s all?’
‘I’ve heard what I needed to. Take your time,’ he said, picking up the bill and heading for the door.
He was out on the street, looking for a taxi, when his phone rang. It was Yukawa. The physicist said he had something to tell Kusanagi about the poisoner’s trick.
‘I need to check something, urgently. Can you meet?’
‘Sure, I’ll come right over. But what do you need to check at this point? I thought you were pretty confident about your theory.’
‘I am confident. That’s why I need you to come as quickly as you can,’ Yukawa said, and hung up.
*
About thirty minutes later, Kusanagi was walking through the front gate of Imperial University.
‘When I started reflecting back on the case, with the assumption that Ayane Mashiba used the trick I described, something kept bothering me – and I thought it might be useful to your investigation,’ Yukawa said as soon as the detective entered the room.
‘Sounds important.’
‘Very. What I need to ask you is this: what did Ayane do first when she returned home after the murder? You were with her at the time, correct?’
‘That’s right. Utsumi and I gave her a ride home.’
‘What was the first thing she did when she walked in the door?’ Yukawa asked.
‘The first thing? Well, she took a look at the scene—’
Yukawa shook his head. ‘No. She went into the kitchen. She went into the kitchen to get water. Am I right?’
Kusanagi gaped. The moment played out again in his memory. ‘Actually, you’re right. She did go to get water.’
‘What did she get water for? She would need a particularly large amount, if my theory is correct,’ Yukawa added, a twinkle in his eye.
‘She watered her flowers. Said something about how it bothered her that they were all wilted. She put water in a bucket, and took it upstairs to water the plants on the second-floor balcony.’
‘That’s it!’ Yukawa said, pointing at Kusanagi. ‘That completes the trick.’
Kusanagi frowned. ‘I think I know what you’re getting at, but explain it to me anyway.’
‘You see,’ Yukawa began, ‘I tried thinking as the killer would think. She knew there was poison in the filter when she left the house. And, as she had hoped, her target drank the water and died. But that’s not enough. There could still be poison left over in the filter.’
Kusanagi straightened his back. ‘That’s true.’
‘It would be dangerous to leave it like that. If someone happened to drink it, she might have another body on her hands. Not to mention it would tip the police off to her trick. So she would have to find a way to destroy the evidence as quickly as possible.’
‘So she watered her flowers …’
‘With water from the filter, no doubt. A bucketful would be enough to nearly completely wash the poison out of the system. So much so that, without a lab as precise as Spring-8, we never would’ve been able to detect it. She was going on about her flowers, and destroying the evidence right in front of your noses.’
‘So that water –’ Kusanagi began.
‘– is your evidence, if there’s any left,’ Yukawa finished. ‘Even if finding trace particles of arsenous acid in the water filter isn’t enough to prove how she did it, proving that a deadly amount of arsenous acid had come out of that water filter on the day of Mr Mashiba’s death would probably be enough to prove my theory.’
‘I just told you, she used the water on her flowers.’
‘Then check the soil in the planters. I’m sure Spring-8 wouldn’t have any trouble finding arsenous acid if it’s in there. Though it might be difficult to prove that it came from the water she used at that time, at least it’s another piece of evidence.’
While he listened to Yukawa talk, something was tugging at the back of Kusanagi’s mind – something he couldn’t remember, something he’d forgotten that he even knew.
Suddenly it dislodged itself from the depths of his brain. Kusanagi gasped. He looked intently at Yukawa.
Yukawa stared back at him. ‘What? Is there something on my face?’
Kusanagi shook his head. ‘I need a favour. Actually, consider it a formal request from the Metropolitan Police Department’s Criminal Investigation Section to Imperial University’s Professor Manabu Yukawa.’
A hard look came over Yukawa’s face. He adjusted his glasses with the tip of a finger. ‘Go on.’
THIRTY-ONE
Utsumi stood in front of the door, looking at the now-familiar nameplate. Anne’s House. According to what Kusanagi had told her, it might as well have read ‘Ayane’s House’. After moving in, the widow had almost entirely cancelled classes.
Kusanagi, standing beside her, nodded. Utsumi pressed the doorbell.
A long interval passed without an answer. She was about to press the button again when a voice came over the intercom.
‘Yes?’
It was Ayane.
‘Hello, it’s Detective Utsumi from the Metropolitan Police.’ Utsumi leaned in close to the speaker, talking quietly so the neighbours would not overhear.
After a moment of silence, Ayane said, ‘Oh, Detective Utsumi. How can I help you?’
‘There’s something I need to ask, if it’s all right?’
Another pause. Utsumi could picture Ayane standing by the intercom inside, thinking.
‘I’ll be right there,’ she said at last.
Utsumi and Kusanagi exchanged glances. He swallowed.
They heard the sound of the door being unlocked. Ayane seemed surprised to see Kusanagi there as well.
Kusanagi lowered his head. ‘Sorry to drop in on you unexpectedly.’
‘I didn’t know you were here too, Detective Kusanagi,’ Ayane said with a smile. ‘Please, come in.’
‘Actually,’ Kusanagi said, ‘can you come with us to Meguro?’
The smile evaporated from Ayane’s face. ‘The Police Station?’
‘Yes. There are a number of things we’d like to go over with you. I’m afraid some of them are a bit delicate …’
Ayane stared at the detective. Utsumi followed her eyes, looking up at Kusanagi in profile. There was a look of sadness, even regret, in his face.
If she didn’t know why we were here before, she knows now, Utsumi thought.
‘I see,’ she said. A strangely gentle light came into her eyes. ‘I’d be happy to go along with you. But I need to get some things. Won’t you wait inside? It’s against my nature to leave guests lingering in the hallway.’
‘Certainly, if you don’t mind,’ Kusanagi replied.
She opened the door wider and invited them in.
The inside of the classroom was neat and tidy. She had obviously packed away some of the furniture she’d set up for her classes. Only the large table in
the middle of the room remained exactly as it had been.
‘I see you haven’t hung up that tapestry yet,’ Kusanagi said, with a glance at the wall.
‘Surprisingly, I haven’t had the time.’
‘Really? You should definitely put it up. It’s such a nice pattern, like something from a picture book.’
She looked around at him, still smiling. ‘Thank you.’
Kusanagi’s eyes went out to the balcony. ‘I see you brought over your flowers.’
Utsumi glanced out at the balcony, too. She could see flowers in a variety of colours on the other side of the glass doors.
‘Just a couple of them, yes,’ Ayane answered. ‘I had a moving company help me bring over some stuff.’
‘That’s good. They look well watered.’ Kusanagi’s gaze lingered for a moment on the large watering can just inside the doors.
‘That watering can has really come in handy,’ Ayane said. ‘Thank you again.’
‘Glad it could be of service,’ Kusanagi said, looking back at her. ‘Please, don’t mind us. Do what you need to get ready.’
Ayane nodded and headed towards the next room; but before opening the door, she turned. ‘Did you find something?’
‘Excuse me?’
‘Did you find something out about the case? Some evidence, or a new lead? That’s why you’re bringing me in, isn’t it? More questions?’
Kusanagi took a sidelong glance at Utsumi before returning his gaze to Ayane. ‘Something like that, yes.’
‘What did you find? Or can you not tell me that until we’re at the station?’ Her tone was as light as if they were discussing the weather.
Kusanagi looked down at the floor for a moment in silence before saying, ‘We found out where the poison was. We had to run several tests, but it’s become very clear that it was inside the water filter in your kitchen.’
Utsumi was staring at Ayane’s face; barely a ripple passed across the woman’s benign expression. Her eyes as she looked towards Kusanagi were calm.
‘I see. In the filter,’ she echoed, no trace of surprise in her voice.
‘The problem was figuring out how the poison got into the filter. Based on evidence found at the scene, there was really only one method the killer could have used. And, based on this method, there’s only one possible suspect.’ Kusanagi stared at Ayane. ‘That’s why we need you to come with us.’