Chapter 62: The Truth Is Just That Simple

However...
"What did you say? No fingerprints or DNA evidence belonging to Keita Katase was found anywhere in Yajima Rika's apartment?"
That's insane.
No matter how incompetent this bunch of people usually was, they shouldn't have turned up absolutely nothing.
Besides, he supposedly went there to have an affair; who could guarantee a whole year of illicit meetings without leaving a single trace?
If this were true, Edmond Locard's coffin lid would fly right off.
Newton's coffin lid might spin endlessly in the world of Conan, but no matter how bizarre the laws of physics became in this universe, Edmond Locard's coffin lid remained an untouchable taboo that no one dared challenge.
Therefore, as Conan loved to say, there is only one truth.
Keita Katase had genuinely never been there.
Hence, he was never having an affair with his father's mistress.
Among this stereotyped family, a normal person had actually appeared.
Furthermore, faced with undeniable proof, his shock upon witnessing Yajima Rika's infidelity might genuinely have been due to the fact that she dared to betray his father...
Perhaps he had truly accepted this "stepmother" who was more than a decade younger than him...
What a deeply filial and touching son!
However, it wasn't a total loss.
Under the illumination of the ultraviolet light, numerous traces of male fluids were discovered throughout the apartment.
Clearly, Miss Yajima Rika really knew how to have a wild time.
Although samples had been sent for testing and the results weren't out yet, considering the complete absence of Keita Katase's fingerprints anywhere in the room, the odds were high that this stuff wouldn't match him either.
Oh no, my reputation rating with Kujo was about to take a hit.
Yet there was no help for it; evidence was evidence, entirely irrefutable.
Upon returning to the Metropolitan Police Department, Megure saw Ji Yi slumped over his desk with an expression of utter despair for the first time.
It was also the first time he had ever seen Ji Yi looking so utterly stumped by a case.
"Brother Higashino, that's just how cases go sometimes." Megure felt he could relate to Ji Yi's suffering, having encountered such situations frequently himself, so he prepared to comfort the seemingly inexperienced Ji Yi with the wisdom of a veteran. "Take the case at Diplomat Ikemura's house, for example. If Brother Kudo hadn't pointed out that the locked room never existed at all, and that the culprit merely exploited the psychological blind spot of an eyewitness to manufacture a 'locked room', we would never have figured out that the culprit was the wife—even the son of the Osaka Prefectural Police Chief was fooled."
"Wait, Inspector, what did you just say?" Ji Yi suddenly perked up.
"The son of the Osaka Prefectural Police Chief was fooled too?"
"The sentence before that."
"We could never have figured out that the culprit was the wife?"
"No, the sentence before that one."
"The locked room never existed at all, and the culprit merely exploited the psychological blind spot of an eyewitness to manufacture a 'locked room'?"
"I understand!"
Ji Yi leaped to his feet.
He grabbed the phone and dialed immediately.
"Yes, I need the contact information for the building security guard, Mamoru Imamura," Ji Yi said, calling the apartment's management office. "What did you say? Today was supposed to be his shift, but he's absent?
"Please give me his home address right away!"
Ji Yi hurriedly jotted down the address: "Got it, thanks a lot."
He immediately summoned his team.
Before they could leave, however, the phone rang again.
He picked it up, and it was Heiji Hattori on the other end.
"I found a corpse."
Heiji Hattori dropped a bombshell right at the start.
-----------------
Deceased: Mamoru Imamura.
Occupation: Building security guard.
Ji Yi stared at the corpse before him, a sense of irony washing over him.
Here it was, the quintessential trope in detective novels: just as you uncover a crucial clue, the vital witness makes their entrance in the form of a corpse.
"I surmise the cause of death is the red wine on the table, and there is a scent of bitter almonds in his mouth..." Heiji Hattori began his performance.
Cyanide—clearly an extremely hazardous substance, yet in Beika Town, purchasing it was probably simpler than buying table salt.
Evidently, today was another episode where the reliable workhorse cyanide made a spectacular appearance.
However, the bottle of red wine on the table was quite unusual.
It was certainly not something a mere building security guard could afford.
Ji Yi sighed.
This truly was his own miscalculation; after repeatedly confirming that Mamoru Imamura's testimony was correct, he had stopped paying attention to him.
From this perspective, Heiji Hattori actually had some competence after all. Could it be that after hitting rock bottom during the case at the diplomat's residence, he had experienced a massive rebound?
"Inspector, I think this case must be related to the previous apartment fall-from-height case," Heiji Hattori analyzed thoughtfully. "It's just that I haven't quite figured it out yet..."
Huh? So you actually didn't know?
Ji Yi was slightly bewildered. "If you hadn't figured out the connection, why did you come looking for him here?"
"I just figured that since I couldn't crack the answer to this building's locked room mystery, I might as well come and ask the security guard who is most familiar with the building's structure; perhaps I could find something the police missed during their questioning earlier." Heiji Hattori gave his signature, naive chuckle while rubbing the back of his head.
"..."
So you simply didn't trust our police force's investigative competence, you jerk!
On second thought, though...
Considering Otaki, who was basically Megure's equivalent by Heiji's side, his worry didn't seem entirely unjustified...
So you really can't blame detectives for taking matters into their own hands—when on earth are you cops going to start acting like competent human beings before opening your mouths!
"Alright, as for this case, I've pretty much figured it out," Ji Yi announced.
"You've figured it out?" Heiji Hattori's eyes widened; he was still completely in the dark.
"Just like the case at Diplomat Ikemura's house, this so-called locked room is not a locked room at all," Ji Yi replied.
"Not a locked room?" Heiji Hattori was momentarily stunned before comprehension dawned on him.
He flashed a confident smile. "I see. This case is truly full of coincidences, isn't it?"
-----------------
Everyone had gathered at the apartment building.
"The inspector said he's already found the killer who murdered Sayo, is that right?" Shingo Katase got straight to the point. "If so, why gather us all here?"
"Because the culprit is among you!" Heiji Hattori delivered the classic line.
"..." In reality, one always felt that line sounded rather awkward when spoken aloud.
"Impossible! Aside from Ms. Yajima, none of us have any records of entering the building," Keita Katase immediately countered. "That means this was a locked-room murder, and it's completely impossible for us to have entered that locked room!"
"Is that so? The prerequisite for a locked-room murder is that the locked room must actually exist, but in this case, I don't believe a locked room exists at all," Heiji Hattori smiled.
"No locked room?" Jun Arizawa was puzzled. "Even when Sayo and I entered and left together previously, the doorman required me to register. How could anyone enter or leave the apartment without leaving a record?"
"The answer to that is naturally very simple," Ji Yi said. "The foundational condition that made this locked room possible was the presence of a security guard at the apartment.
"However, a security guard is a human being, not a surveillance camera, so naturally various unexpected situations will arise."
"You mean..." Everyone finally caught on.
"The reason the culprit was able to enter this apartment freely is, of course, because the security guard, Mr. Mamoru Imamura, was not at his post at the time.
"The truth is just that simple."