She started the video. A few seconds later, a plump man in a bomber jacket appeared in the left-hand corner of the screen. He clambered into one of the vans and drove off.
Utsumi rewound the footage slightly, froze a frame, and enlarged the man’s face.
Kusanagi had brought a copy of the photograph from Shusaku Tojima’s driver’s license. He showed it to Mamiya. “We think it’s the same person.”
Mamiya narrowed his eyes and scrutinized the picture. “Tojima procured the liquid nitrogen from his own factory?”
“We think it probable, yes.”
“Any evidence?”
“The quantity of liquid nitrogen in the factory’s storage tank is monitored on a daily basis. Between the Friday and the Monday, it decreased by roughly twenty liters. With liquid nitrogen, there’s always going to be a small percentage that evaporates. The tank manager, however, was adamant that it had never gone down so much before.”
“I see. Still, that’s hardly decisive,” Mamiya said grumpily. “Did you manage to track the minivan’s movements?”
“He handled that,” Kusanagi said, with a jerk of the chin in Kishitani’s direction.
“We went through the footage from the security cameras in the vicinity of the factory. So far, we’ve not been able to find the minivan in question,” Kishitani said to Mamiya. “N-System didn’t catch it on the main road, either.”
“Is there a way to get from the factory to the crime scene while avoiding N-System?”
“It’s possible, but it involves such a major detour that no one would ever decide to go that way. You’ve got to remember that ordinary civilians have no idea where the N-System monitoring points are located,” Kishitani said.
“Moving on,” said Utsumi. Tapping her keyboard, she pulled up an image of the parking lot. The minivan drove back in and a man resembling Tojima climbed out and walked off.
“The time stamp says 1:51. Since we know Tojima left the factory at 1:20, that gives him roughly half an hour. Even by the shortest route, it still takes over ten minutes to get to the crime scene. He certainly wouldn’t have taken a roundabout route.”
Mamiya crossed his arms on his chest and turned to Kusanagi. “Has Tojima got an alibi?”
“Yes, he has,” Kusanagi shot back. “He was with his friends at the neighborhood association from around three P.M. He did step outside occasionally, but never for very long. He stayed with them until early evening, when he went to Namiki-ya. His alibi checks out.”
“In other words,” muttered Mamiya, “Tojima isn’t the principal.”
“No, I don’t think he is,” Kusanagi said. “We should probably think of it in these terms. Tojima used the minivan to take the liquid nitrogen out of the factory and deposit it somewhere, before driving back. Somebody else — not him — then took the liquid nitrogen from there to the crime scene.”
“And that somebody else is the principal. But who is it?”
“We don’t know. Our prime suspect is Yutaro Namiki, but, as you know, he has an alibi. The same’s true for Masumura.”
Mamiya groaned softly, knitted his fingers behind his head, and leaned back in his chair.
“That fellow... Detective Galileo... what does he have to say? Hasn’t he been able to come up with one of his beautiful theories?”
“He has come up with what he calls a ‘for-the-time-being solution.’”
“What’s that supposed to mean?”
“I should warn you, it’s an outlandish theory...”
It was a theory Yukawa had unveiled after he’d come to the same conclusion: that Tojima wasn’t the principal.
“Masumura is one accomplice and Tojima is probably another. But are they the only accomplices who took part in the crime? Take Tomoya Takagaki, for example. While he appears to have an alibi, there’s also a roughly thirty-minute chunk of time that’s unaccounted for. What was he doing in that time? In addition, if the helium tank we found in the clump of weeds was only a decoy, that makes it possible that the murder was committed before the helium was stolen at 4:30 P.M. — something that undermines the perfect alibi of the Niikuras. Taken all together, do these facts amount to anything significant?”
Yukawa’s theory had hit him like a bombshell, Kusanagi went on. The physicist was proposing that a large number of people might have been involved in committing the crime.
Yukawa had emphasized that what he was putting forward was “no more than a for-the-time-being solution.”
“Up to a point, at least, I know all the people involved. They’re all good, decent, ordinary folk. I know that they loved Saori Namiki and probably hated Hasunuma. At the same time, I just can’t see them taking part in a murder. Just because there are, say, ten accomplices doesn’t mean that each of them only suffers one-tenth of the normal pangs of conscience. That’s why my hypothesis remains incomplete.”
Yukawa had delivered this speech with a melancholy expression on his face. Kusanagi understood Yukawa’s point: It was hard to believe that so many people would participate in a murder plot.
Seeing that Kusanagi had finished, Mamiya weighed in. “I agree with that last point of Yukawa’s,” he said. “The multiple-accomplice theory is certainly an interesting one, but with a crime as atrocious as murder, it’s difficult for a lot of people to preserve a united front. More people just multiplies the risk, especially when the crime is detected.”
“Still, sir, it looks like Masumura and Tojima are definitely. And since there’s got to be something to connect the two of them, it’s hard to think that the connecting link would be anyone other than Namiki...”
“Yet Namiki, the crucial figure, has an alibi.” Mamiya crossed his arms. “Which means we end up going around in circles.”
“This is what we need to look at, if we want to break the logjam.” Kusanagi pointed at the computer display, which was showing a still of the minivan parked in the Tojima-ya Foods lot. “Our experiment proved that roughly twenty liters of liquid nitrogen were needed for the crime. A standard tank for liquid nitrogen is around two feet high, around a foot in diameter, and weighs around fifty-five pounds when full. The question we have to answer is, once Tojima took it out of the factory, how did a second person transport it to the crime scene?”
“Okay, so the helium tank has now become a tank of liquid nitrogen. Regardless which gas it was, the perpetrator still had to transport something very large. We haven’t yet found any such a person, have we?”
“Our focus until now has been the security cameras in the vicinity of the park from which the helium tank was stolen. We also focused on a time period after four thirty, when the theft of the tank took place. What we need to do now is to conduct interviews and analyze the security camera footage over an enlarged area and a longer time frame.”
Although Kusanagi’s tone was confident, in his heart of hearts he still felt uneasy. Not even Professor Yukawa had managed to put together a complete hypothesis. He had no faith that the investigation was proceeding along the right track.
Part Three
“As you yourself have said, what other explanation can there be?”
Poirot stared straight ahead of him.
“That is what I ask myself,” he said.
35
The bar was located about a ten minutes’ walk from Kikuno station. It was on a narrow side street in a small modern building. Standing at a certain remove from the busy shopping district, it didn’t seem an ideal location but as the place had been in business for years, it probably benefited, like Namiki-ya, from a core of regular customers.