“…It’s Miss Unoki?” he asked; his voice was trembling.
Shiroshi nodded. “Yes. As a matter of fact, both Mr. Tosu and I realized she was the culprit when we saw the scene of Ishizuka’s murder.”
“……Huh?” Seiji looked dumbfounded.
Raising an index finger, Shiroshi began to explain, as though soothing a pet dog who wasn’t too bright. “First, there was the lack of bloodstains in Room 601, the scene of the crime.”
As he listened, Seiji thought back. Ishizuka had cut his hand on that piece of glass and had left a regular trail of bloodstains all the way down the corridor from the dining car to his compartment. However, they hadn’t seen any blood at all on the wood flooring just inside the door of Room 601 or on the expanse of carpet farther back. In addition, Ishizuka’s corpse had been lying in the center of the room, and since there was no sign that the bleeding had been stanched with a handkerchief or anything else…
“There should have been a trail of bloodstains like the one in the corridor across the floor of the compartment as well, and yet there wasn’t. The first possibility was that the killer had cleaned the floor after his death. However,” Shiroshi went on, “if the bloodstains could be wiped away that neatly, it meant that Ishizuka hadn’t walked over the carpet. In other words, he died just after entering the room—on the wood flooring.”
“Huh?”
It was true—it would have been hard to miss any dirt at all on that ivory carpet.
If Ishizuka had walked around on it with blood dripping from his palm, it would have been impossible to make it look as if he hadn’t. The killer would only have been able to clean up the blood on the wood flooring. And yet…
“Th-then why was Ishizuka’s corpse where it was?”
“The killer moved it after death. She waited for his wound to stop bleeding, then dragged his body into the center of the room.”
But why?
“In order to obscure the time at which the crime took place. If the bloodstains and the corpse had remained in their original states, it would have been clear at a glance that he had been attacked immediately after returning to Room 601 from the dining car. There is only one passenger who would have been inconvenienced by that situation.”
“Huh? Wh-who…? Oh!” A second later, Seiji got it.
When the deranged Ishizuka had bolted out of the dining car, Ms. Nomura had just come back from escorting Mao to her room. In other words, everyone except Mao had been in the dining car. That made her the only possible culprit. And yet…
“B-but how did she get into his room?”
That was the fundamental problem.
At the time, Room 601 had been locked. Getting inside to kill Ishizuka should have been impossible.
“Oh, I know. Did she wait for him in the corridor, then jump him from behind as he unlocked the door…or something?”
“There are no obstacles in the corridor of Car Six that could serve as hiding places. Besides, Miss Unoki is a high school girl of average build. Mounting a brute-force attack on a large man would have been too great a risk, even if she caught him by surprise.”
True. Besides, if the attack had developed into even a brief struggle, Tosu and Shiroshi might have seen it as they ran after Ishizuka.
“Then, um, how on earth did she—?”
“When Ishizuka returned to Room 601, Miss Unoki was already waiting inside. Thanks to the bug she planted in the dining car, she knew exactly when Ishizuka would return. She attacked him with the syringe just as he stepped through the door.”
“…Huh?” No, no way, that’s ridiculous! “W-wait just a minute! Ishizuka had the room key, didn’t he? How could Miss Unoki get inside to ambush him?!”
“The hint was that the key in the pocket of Ishizuka’s suit was perfectly clean.”
That was true. Even though he’d held it in his bloodied hand, the room key had been spotless.
“The second hint was that the key to Room 201 had gone missing. Do you remember how we found it in the pocket of that jacket when we searched the compartment?”
“Yes. The jacket was hanging in the closet, but Kaganuma tossed it on the floor, and then— Ah!”
Right. Mao had picked it up and returned it to the closet.
“That is when Miss Unoki acquired the key to Room 201. Next, when we were inspecting everyone’s compartments, she saw that Ishizuka kept his key in his suit pocket. Then she activated the smoke machine in the lounge and, in the confusion, took the key for Room 601 from Ishizuka’s pocket and replaced it with the key to Room 201. One could say that Kaganuma’s murder was an afterthought.”
“A-an afterthought…” For a moment, Seiji’s mind went completely blank, but he managed to shake the dizziness away. “B-but wouldn’t that have been pretty obvious? I mean, the room numbers are on those cork tags.”
“She tore it off. Everything else is the same, down to the color of the ribbons,” Shiroshi said, as casually as ever. “That’s why she couldn’t put the key to Room 201 back. To make matters worse, Ishizuka’s wounded hand had gotten it quite bloody… I would imagine she dropped it down a drain.”
Then something occurred to Seiji. “But then…when Ishizuka got back to Room 601, the key he had was the key to 201, right? So he couldn’t have opened the door—”
“That was an astute observation, Seiji. Especially for you,” Shiroshi said, ruffling his hair.
…Right. That was such a routine move by now that it didn’t even warrant a comeback.
“Frankly, it was quite simple: As Ishizuka tried to unlock the door, Miss Unoki released the lock from the inside.”
Oh, I see, Seiji thought. The compartment doors had peepholes. She’d only had to peek through it and twist the thumb-turn knob when Ishizuka raised the key to the sensor.
“…So it really was Miss Unoki,” he murmured, groaning.