Yukawa chuckled. ‘Don’t start jumping at shadows yet. Like I said, I’m only interested in this because it’s piqued my scientific curiosity. Which means, by the way, that should I lose interest, I’m out. That’s why I want you to let me into that house again. To make my final determination.’
The detective looked his friend directly in the eye. Yukawa looked back, cool as ever.
Kusanagi hadn’t the slightest idea what the physicist was thinking. This was nothing new. Kusanagi knew that there was a point when he just had to let go, and trust that Yukawa would come to the rescue as he had so many times before.
‘I’ll call Mrs Mashiba. Give me a second,’ he said, standing and pulling out his phone.
Going to a quiet corner, he dialled Ayane’s number, and when she answered he asked if it was all right for him to let himself in one more time. ‘I’m sorry to make this request yet again, but there was one last thing we really needed to check.’
He could hear her give a little sigh on the other side of the line. ‘You don’t need to check with me every time, you know,’ she said. ‘It’s an investigation; I expect you to be going in and out frequently. I hope you find something.’
‘Thanks. I’ll water the flowers while I’m there.’
‘Thank you so much. It’s a big help.’
Kusanagi went back to the table. Yukawa was looking up, observing him as he approached.
‘You got something to say?’
‘I was just wondering why you felt the need to get up in order to make the call?’ Yukawa asked. ‘Was there something you didn’t want me to hear?’
‘Of course not. All I did was get permission to go inside her house.’
‘Huh.’
‘What is it now?’ Kusanagi glared.
‘Oh, nothing. It’s just, when I watched you making the call, I couldn’t help but think you looked less like a detective, and more like a salesman making a pitch to an important customer. Is there some reason you have to tread lightly around this Mrs Mashiba?’
‘I was asking if we could go into her house. It’s a sensitive subject.’ Kusanagi picked up the bill from the table. ‘Let’s get going. It’s late already.’
They hailed a cab by the station. Sliding into the seat, Yukawa pulled out the magazine he had been reading in the café.
‘You were saying earlier that dinosaur fossils were all bones, but that assumption carries a considerable amount of risk. In fact, it’s an assumption that led many paleontologists to discard a lot of extremely valuable material.’
This again. ‘All of the dinosaur fossils I’ve seen at the museum were bones.’
‘That’s right. That’s because they threw out everything else.’
‘Everything else? Like what?’
‘Say you’re digging a hole and you find some dinosaur bones. Naturally, you get excited and dig them right up, brushing off all the dirt, so you can construct your big impressive dinosaur skeleton. Then you start making observations: “So that’s what a tyrannosaurus jaw looks like”, and “Look at those short forelimbs”. But, it turns out, you’ve already made a terrible error. In 2000, a certain research group dug up a chunk of dirt with some fossils in it and ran the whole thing through a CAT scan without cleaning it all. And guess what? They found the heart. The dirt trapped inside the skeleton had preserved the shape of the creature’s internal organs perfectly. These days, it’s standard practice to run a CAT scan on all fossils.’
Kusanagi grunted. ‘That’s pretty interesting, actually,’ he admitted. ‘I’m just not sure what it has to do with anything. Or were you just making small talk?’
‘When I first heard about the discovery, you know what I thought? I thought: here is a very clever trick, one that it took several millennia for Mother Nature to pull off. You can hardly blame the paleontologists who cleaned the dirt off the first dinosaur bones they discovered. But, as it turns out, the dirt they discarded as “useless” turned out to be extremely important.’ Yukawa closed the magazine. ‘You may have heard me mention the process of elimination, by which we invalidate one hypothesis at a time, eliminating all the possibilities until we’re left with a single truth. However, when there is a basic error in the way we form our hypotheses, that method can lead to extremely dangerous results. Sometimes, when we’re too eager to get those bones, we end up missing the point.’
So this conversation does have something to do with the investigation. ‘You think we made a mistake in our thinking about the route of entry for the poison?’
‘That’s what I’m going to go and check now. It’s just possible that our killer is quite the scientist,’ Yukawa added, half to himself.
The Mashiba residence was quiet and dark. Kusanagi retrieved the key from his pocket. He had already tried to return both copies of the key to Ayane, but she’d left him with one, saying that the investigators might still have need of it and as long as she didn’t have any plans to go home, it was no use to her.
‘The funeral’s over, isn’t it? No plans to do anything at the home?’ Yukawa asked as he was taking off his shoes.
‘She didn’t mention anything. The husband wasn’t a very religious man, so they did a flower ceremony in place of a formal funeral. There was a cremation, but none of the other usual observances.’
‘Sounds like a logical way to go about doing things. Maybe I should put in a request to receive the same treatment when I die.’
‘Fine by me,’ Kusanagi grunted. ‘I’d be happy to make the arrangements.’
Inside, Yukawa walked swiftly down the hallway. Kusanagi watched him go, then made his way up the stairs, opening the door to the master bedroom. He opened the sliding door that opened onto the balcony and picked up the large watering can on the other side – a purchase he had made at the home repair centre yesterday after Ayane asked him to water the flowers.
Can in hand, he went back downstairs. He found Yukawa in the kitchen, under the sink again.
‘Didn’t you check under there last time?’ he called out.
‘Aren’t you police always talking about fine-toothed combs? That’s all I’m doing,’ Yukawa countered. He was carefully examining the space by the light of a small penlight. ‘Oh well – no sign that anyone touched anything in here at all.’
‘Didn’t you check that last time?’
‘Yes, but I thought it might be prudent to go back to square one. We have the dinosaur fossil in front of us, all we have to do is avoid carelessly removing the dirt.’ Yukawa turned towards Kusanagi; a suspicious look came into his eyes as he caught sight of the object in the detective’s hand. ‘What’s that?’
‘Never seen a watering can before?’
‘Oh yeah, I seem to recall you sending Kishitani off to water the plants last time. Is this all part of a new PR campaign? “The police – we’re not just public servants, we’re servants”?’
‘Laugh it up,’ Kusanagi said, pushing past him to get to the sink. He placed the can under the tap and opened it all the way.
‘That’s an awfully big can,’ Yukawa noted. ‘Doesn’t she have a hose in the garden?’
‘This is for the flowers on the second floor. The balcony’s covered with planters.’
‘A policeman’s work is never done,’ Yukawa said, grinning, as Kusanagi headed out of the kitchen.
Back up on the second floor, Kusanagi began to water the flowers. Though he couldn’t have named a single one of them to save his life, even he could tell that the plants weren’t doing so well. Better not let them wilt. The watering complete, he shut the balcony door and hurried back through the bedroom. Even if he was here by permission, it didn’t feel right to linger in someone else’s sleeping quarters.
When Kusanagi got downstairs Yukawa was still in the kitchen. He was standing with his arms crossed, glaring at the sink.
‘Why don’t you just come out with it and explain to me what you’re thinking? Because if you don’t, there’s no way I’m giving you special treatment like this again.’
r />
‘Special treatment?’ Yukawa asked, lifting an eyebrow. ‘Is that what you call it when one of your officers barges into my laboratory and involves me in yet another tangled, hopeless investigation?’
Kusanagi let his hands fall down to his hips and stared back at his friend. ‘I don’t know what Utsumi said to you, but it has nothing to do with me. In fact, if you wanted to check the house, why didn’t you just call her again? Why drag me into this?’
‘Because a real debate can only happen between two people with opposing points of view.’
‘So you oppose the way I’m running this investigation? I thought you said I was on to a “sure thing”.’
‘I have nothing against you running a proper investigation. I just don’t like it when people discard angles of attack just because they seem improper or unlikely. Even if only the slightest possibility remains that something might’ve occurred, one shouldn’t disregard it too easily. Don’t toss out the dirt.’
Kusanagi shook his head in exasperation. ‘So what’s the dirt, in this case?’
‘Water,’ Yukawa replied. ‘The poison was mixed into the water. At least, I think so.’
‘Now we’re back to the victim-washing-the-bottle theory.’ Kusanagi snorted.
‘I’m not concerned with the bottle. There are other sources of water.’ Yukawa pointed at the sink. ‘That tap, for one. Plenty of water there.’
Kusanagi stared back into Yukawa’s cool eyes. ‘You’re serious?’
‘It’s a possibility,’ Yukawa said with a shrug.
‘But Forensics found nothing unusual about the water line at all.’
‘Yes, Forensics did analyze the tap water. But they only analyzed it in order to tell whether the water left in the kettle was from the tap or from a bottle. And I understand they couldn’t tell the difference, because of all the tap water residue that had built up inside the kettle.’
‘But if there was poison in the tap water, wouldn’t they have found it?’
‘It’s possible that by the time they checked, the poison had already washed out entirely.’
‘But the victim only used bottled water when making coffee.’
‘So I hear,’ Yukawa admitted. ‘But who told us that, exactly?’
‘The wife.’ As soon as Kusanagi said it, he bit his lip and stared at Yukawa. ‘And of course you think she’s lying, though you haven’t even met her. What ideas has Utsumi been putting in your head?’
‘She has her own opinion, and she’s entitled to it. All I’m doing is formulating a hypothesis, based on objectively observable evidence.’
‘And does your hypothesis tell you the wife is the killer?’
Yukawa ignored him. ‘I gave some thought to the question of why the wife told you about the bottled water. There are two possibilities. One is that the statement “Mr Mashiba only uses bottled water” is false. The other is that it’s true. If the statement is true, no problem. The wife is simply doing her best to aid the investigation. I think Utsumi would still say the wife is guilty, but I’m not half as stubborn. The real problem here is if the statement is false. Firstly, because lying would suggest that the wife was somehow involved with the crime – but it also means that there’s some reason for her to tell that particular lie. So I considered the effect that her statement about the bottled water had on the course of the police investigation.’ Yukawa wet his lips and continued. ‘First, the police investigated the empties to make sure there was no poison in any of them. At the same time, they found poison in the kettle. This led to the assumption that it was likely that the killer put the poison in the kettle. Which naturally provides the wife with an ironclad alibi.’
Kusanagi shook his head slowly from side to side. ‘That’s where I don’t follow you. Even if she hadn’t given us that tip, Forensics would’ve checked the water line and the bottles. In fact, by telling us he only used bottled water, she actually hurt her alibi. For example, Utsumi still hasn’t given up on the idea that the poison was in a bottle to start with.’
‘That’s just it,’ Yukawa said. ‘Many people would think exactly the same thing as Detective Utsumi. It made me wonder if the whole bottled water testimony might be a trap laid to catch just that kind of person.’
‘Huh?’
‘Anyone who suspected the wife wouldn’t be able to let go of the idea that the poison was added to the bottled water, because they’d think there was no other way for her to have done it. But if she used an entirely different method to poison her husband, anyone still obsessed with the bottled water would be left spinning their wheels for an eternity, never reaching the truth. If that’s not a trap, what is? That got me thinking. If the husband didn’t use bottled water—’ Yukawa stopped suddenly in midsentence. His face was frozen, his eyes looking over Kusanagi’s shoulder.
Kusanagi turned around, then stood, as startled as Yukawa.
Standing there in the entrance to the living room was Ayane Mashiba.
SIXTEEN
‘Er, hello … we let ourselves in,’ Kusanagi managed after a long pause. He realized it was an idiotic thing to say almost as soon as the words left his mouth. ‘Here to check up on things?’
‘No,’ Ayane replied. ‘Just here for a change of clothes. Might I ask who that is?’
‘Oh, this is Yukawa. He’s a physics professor at Imperial University.’
Yukawa remained silent.
‘A university professor?’ Ayane asked, clearly puzzled.
‘And my friend, actually,’ Kusanagi explained. ‘He often helps our department with, er, scientific investigations … which is why he’s here today.’
‘Oh, I see,’ Ayane replied. Though she was clearly still puzzled, she said no more about him. Instead she asked, ‘Is it all right for me to touch things?’
‘Of course. You’re free to do whatever you like. I’m sorry we’ve taken so long.’
‘No need to apologize.’ Ayane moved towards the hallway. But after two steps she stopped, once again turning to face Kusanagi and the physicist. ‘I’m not sure if I’m allowed to ask, but what are you looking for, exactly?’
‘Oh, right,’ Kusanagi began, wetting his lips. ‘Well, we’re still having trouble determining the route by which the poison got into the coffee, so were doing some follow-up tests. I hope you don’t mind. We’ll be done soon.’
‘No, I don’t mind at all,’ she said. ‘It wasn’t a complaint, just curiosity. Don’t let me interrupt. I’ll be upstairs if you need anything.’
‘Right, thanks.’
Ayane gave Kusanagi a curt bow and turned to leave, but Yukawa spoke suddenly. ‘Might I ask a question?’
The widow stopped again. ‘Yes?’ The expression on her face made it clear that she did not trust this newcomer.
‘There’s a water filtration system on your sink here in the kitchen. I’m assuming you regularly change the filter, but do you remember when you last did that?’
‘Oh, that …’ Ayane came around to peer into the kitchen. She frowned as her eyes fell on the sink. ‘Actually, I don’t think I ever changed it once.’
‘Huh? Not even once?’ the physicist said with evident surprise.
‘I was thinking I should call the company and have them do it one of these days. The filter on there is the one they put in just after we moved in, so it’s about a year old. Which, if I recall what the serviceman told me, is right about when you’re supposed to change it.’
‘So the last time the filter was replaced was a year ago?’
‘Did … I do something wrong?’
‘No, no, of course not,’ Yukawa said. ‘I was just curious. And, you probably should go ahead and get it changed. There are data that show old filters can actually do more harm than good.’
‘Well, I’ll do it right away,’ Ayane said. ‘But I suppose I should clean under the sink first. It’s a mess under there.’
‘That’s the same in every house,’ Yukawa said. ‘You should see the roach nest under the sink in our laborato
ry – but I shouldn’t be comparing my lab to a proper residence. You know –’ Yukawa glanced at Kusanagi before continuing. ‘If you had the number of the serviceman handy, I bet Kusanagi here could give him a call for you. No time like the present, after all.’
Kusanagi shot a surprised look back at Yukawa, but the physicist ignored him, instead looking back towards Ayane. ‘Sound like a good idea?’
‘You mean right now?’
‘Yes, if it’s all right. To be honest, it might help with the investigation, and the sooner the better.’
‘Well, if that’s the case, I certainly don’t mind.’
Yukawa smiled and turned again to Kusanagi. ‘There you go. You have your orders.’
Kusanagi glared back at the physicist, but he knew his friend well enough by now to know that he wasn’t doing it on a lark. Whatever Detective Galileo was up to, he had a plan. ‘Could you get the number?’ Kusanagi asked Ayane. ‘If you don’t mind …’
‘Sure, just a moment.’
Kusanagi waited for the widow to leave the room before glaring again at Yukawa. ‘You could’ve at least given me a heads up first.’
‘There wasn’t time. And besides, before you start complaining, I think there’s something you need to be doing.’
‘What?’
‘Call Forensics. You don’t want the filtration system serviceman to destroy any evidence, do you? One of your Forensics guys should handle the actual removal of the filter.’
‘You mean you want Forensics to take the old filter back with them?’
‘Yes, and the connection hose,’ Yukawa said in a low voice. In his eye was the cool gleam of a scientist who’s caught sight of his quarry. Kusanagi swallowed as Ayane returned to the living room.
About an hour later, an officer from the Metropolitan Forensics Division had removed the filter and the filtration system hose from the sink under the watchful eyes of Kusanagi and Yukawa. The Forensics officer took great care in placing the two parts inside an acrylic case, making sure not to disturb the considerable amount of sediment that had built up inside them.