‘That’s really none of their business,’ Tatsuhiko said to his wife. He looked back at the detectives. ‘Or is how they met, and their marriage, somehow related to the case at hand?’
‘I didn’t mean to suggest that,’ Kusanagi said with a wave of his hand. ‘We just don’t have many leads at present, and I thought it might behove us to learn a bit about the Mashibas’ married life.’
‘I understand why you’d want to gather as much information as you can about the victim … but pry too far and you could get into trouble,’ Tatsuhiko said, putting on his lawyer face. There was a look in his eye that Kusanagi interpreted as a mild threat.
‘I’m aware of that,’ the detective said, lowering his head in an apologetic bow before looking back up at the lawyer. ‘Apologies in advance for my next question – but to satisfy our standard operating procedures, I’ll need to ask you how both of you spent your weekend, if you don’t mind.’
Tatsuhiko nodded slowly, the corner of his mouth curling upward. ‘You want our alibis? I suppose that’s to be expected.’
He pulled a small, leather-bound organizer out of his jacket pocket.
Tatsuhiko Ikai had gone to work at his own office on Saturday, after which he went out drinking with one of his clients. On Sunday, he went to play golf with another client, returning home some time after ten in the evening. Yukiko had been at home the whole weekend, and on Sunday her mother and sister had come to visit.
That night, an investigation briefing was held at local precinct headquarters, the Meguro City Police Station. The head officer from the First Investigation Division of the Metropolitan Police Department opened by repeating that they were, in all likelihood, looking at a homicide. It would be hard to explain the presence of the particularly virulent arsenous acid found in the used coffee grounds any other way. If it had been a suicide, the deceased probably wouldn’t have bothered mixing the poison into his coffee – and even if he had, it would have been far more typical for him to mix it into an already brewed cup.
Someone from Forensics had a report on the ongoing investigation to determine how the poison had got into the ground coffee, but there was nothing Kusanagi hadn’t heard before; it could all be summed up with ‘we don’t know’. Forensics had gone back to the Mashiba residence that afternoon, with the intention of examining everything in the house that Yoshitaka Mashiba might have put in his mouth: food, spices, drinks, medicine. The same attention was given to all of the cutlery and silverware in the house. At the time of the briefing, they had already checked eighty percent of the items; so far they hadn’t found traces of poison on anything. The liaison from Forensics suggested that it was unlikely they would find anything in the remaining twenty percent.
This meant that the guilty party had specifically targeted the coffee Yoshitaka was going to drink. This, Forensics informed them, could have been accomplished in one of two ways: the killer could have put poison in the ground coffee, the paper filter, or the cup in advance; or they could’ve mixed it in when the coffee was being made. There was no way of telling which it had been at this point, without finding arsenous acid anywhere else in the house, and with no way of knowing whether someone had been with Yoshitaka when the coffee was made.
Someone else had gone around questioning the neighbours. No one had seen anyone visit the Mashiba residence on that day prior to the time of death. Of course, in a quiet residential neighbourhood like the one in question, people tended not to pay attention to anything that didn’t affect them directly, so they might not have noticed a visitor’s presence.
Kusanagi reported on what he’d learned from talking to Ayane and the Ikais, without mentioning the relationship between Hiromi and Yoshitaka. Before the briefing, Mamiya had told them to keep that under wraps for now, though he had included it in his own report to the head officer from Division. Apparently, the higher-ups felt it was too delicate a matter to spread beyond those directly involved in the investigation until it was proved to have some connection to the case. If word leaked out to the press, it would mean headaches for everyone.
After the briefing, Mamiya called Kusanagi and Utsumi into his office. ‘I want you to go to Sapporo tomorrow,’ he told them.
‘You want us to check on Mrs Mashiba’s alibi?’ Kusanagi asked.
‘You got it. A man having an affair was killed. That makes his lover and his wife both suspects, and we’ve already established that the lover doesn’t have an alibi. Division wants us to narrow in on our perpetrator as quick as we can. Speaking of which, you’ve only got a day up there to do your thing. I’ll make sure the Hokkaido police are ready to help you out any way they can.’
‘The wife said the police contacted her at a hot springs resort – we’ll probably have to go there, too.’
‘Yeah, Jozankei Hot Springs. It’s about an hour out of Sapporo by car. The wife’s family home is in Nishi Ward, right in the city. You can split up and get it all done in a few hours.’
I guess so, Kusanagi thought, scratching his head. Shame on me for even imagining that he’d put us up at the hot springs for a night.
‘What is it, Utsumi? You look like you want to say something,’ Mamiya said.
Kusanagi glanced over to see the junior detective standing with her lips pressed together as if she could barely contain a question.
‘Are we only checking out her alibi for the weekend?’
‘What do you mean?’ Mamiya asked.
‘Mrs Mashiba left Tokyo on Saturday morning, and returned on Monday morning. I was wondering, is that the only time period for which we need an alibi?’
‘You don’t think that’s enough.’
‘I’m not sure. But it seems to me that as long as we don’t know how the poison was mixed into the coffee, or when, we can’t remove her from the list of suspects just by knowing where she was over the weekend.’
‘Wait a second,’ Kusanagi said. ‘We might not know how it was done, but we do know the time. Hiromi Wakayama drank coffee with Yoshitaka Mashiba on Sunday morning and neither of them died then. The coffee must have been poisoned after that.’
‘Are you sure we can say that?’
‘Can’t we? When else could the poison have been put in?’
‘Well … I don’t know.’
‘You think Hiromi Wakayama’s lying to protect the wife?’ Mamiya asked. ‘That would suggest that the lover and the wife were in cahoots, which seems unlikely.’
‘I agree. I don’t think that’s it.’
‘So what’s the problem?’ Kusanagi said, a little roughly. ‘All we need is her alibi from Saturday to Sunday. Actually, we only need it on Sunday to clear the wife. Is there something wrong with that train of logic?’
Utsumi shook her head. ‘No, nothing. It seems perfectly reasonable. I was just wondering if there wasn’t some way of poisoning the coffee that we haven’t thought of, something that wouldn’t require the guilty party to be present at the house on Sunday. Maybe a way to get Mr Mashiba to poison it himself?’
Kusanagi’s eyebrows drew together. ‘You mean someone compelled him to commit suicide?’
‘Not that. They didn’t have to tell him it was poison. What if he thought it was something to make the coffee taste better? A secret ingredient?’
‘A secret ingredient? In coffee?’
‘Like garam masala for curry – you sprinkle on a little before you eat, and it improves the flavour and aroma. Whoever it was could’ve told Mr Mashiba the poison was like that, but for coffee. I know it’s a bit of a stretch … but he could’ve not used it when he was taking coffee with Ms Wakayama, then only remembered it later when he was brewing a cup for himself.’