At exactly nine o'clock in the morning,
the Violent Crimes Unit headquarters in Seoul transformed into a war room. The cold white lights reflected off Detective Kim's face as he analyzed the crime scene with an unmissable gaze.
Kim said while pointing at a timeline displayed on the screen:
"The Purifier… as he calls himself… in his view, he is not a killer… he is not an ordinary person.
He is conducting a remotely controlled theatrical performance.
He never touched the final crime scene with his own hands… he used the hands of others."
Detective Kim turned toward the screen, folding his arms behind his back as he silently observed the images. He stepped closer, then began slowly scrolling through the footage… as if he could see what others could not.
The images stopped at a frame captured by surveillance cameras inside the metro station.
He sighed deeply, then extinguished his cigarette in the ashtray, pressing it down until it completely crumbled.
Detective Kim began explaining the structure of the plan to the team:
"We have two intermediaries."
Assistant Lee asked in confusion:
"Two intermediaries? But we only interrogated one."
Kim turned to him with a sharp look, then continued calmly:
"And neither of them knows the other exists.
The first intermediary, the one we already interrogated, had a purely logistical role: delivering the bag to the last restroom at exactly 18:15 and leaving it there.
He was merely a courier blackmailed due to extramarital affairs."
He paused briefly, then added:
"This is what has been confirmed so far.
The Purifier uses fake identities… and he knows exactly how to erase his trace."
He moved slowly toward the control board, pressed it, and three people appeared on the screen.
"According to surveillance footage, during the time gap between the bag being placed and the head being discovered at 18:25, only three people entered that restroom.
One of them… is our key.
The second intermediary."
Inside Interrogation Room (4), a man sat hunched as if the weight of the world rested on his shoulders. He was not a professional criminal, but a man wearing a formal suit suggesting a high-ranking position, though his eyes were drowning in fear.
Detective Kim sat down and leaned back calmly. A small camera was placed on the table to record the interrogation.
Kim glanced at the suspect.
He noticed his dilated pupils, trembling fingers, and sweat forming on his forehead.
He leaned slightly forward and said in a low voice:
"Let's cooperate.
Around 18:20 last Friday… you entered that restroom.
Did you notice anything unusual?"
The suspect remained silent.
Kim said coldly:
"Silence won't help you.
Tell me… what did you do with the contents of the bag in the last restroom?"
The man pressed his finger hard until his nail turned pale.
Kim noticed it immediately.
He stood up and stepped closer, then whispered while observing every micro-movement:
"There are only two possibilities."
He paused, then added:
"The first…
that you are the killer."
The man panicked instantly and waved his hands desperately.
"No, sir… I swear, I am not the killer!"
Kim continued without changing his tone:
"And since you insist you are not the killer…
then at the very least, you placed the head of the victim, Woo Jin, inside the toilet tank."
He leaned closer and said coldly:
"I'm listening."
The suspect began speaking in a trembling voice:
"Sir… I swear… I didn't know what was inside that sphere… it was hard and heavy, wrapped in something like opaque plastic."
Kim leaned on the table and narrowed his eyes:
"Why did you do it?"
The man broke down crying:
"The messages… they never stopped! They came from different international numbers every time. Photos of me from high school… I was reckless back then, I used to bully my classmates badly…
If those photos are exposed now, I will lose my prestigious job immediately. I have a wife and two children… I can't let my family collapse because of a mistake I made years ago!"
While trying to catch his breath, he continued:
"The sender told me to enter the restroom at exactly 18:10, carrying a key that had been sent to my house beforehand.
But the bag arrived at 18:15.
I had to wait until the first person left after placing it.
Then I went out, unlocked it, and took what was inside."
The suspect continued:
"The sphere was about the size of a football. I placed it inside the water tank as instructed.
The moment it touched the water, I noticed it began to dissolve slightly… and produced a faint bubbling sound.
I was terrified.
The instructions were strict: enter, execute, leave within five minutes.
It felt like an unseen eye was watching me… so I closed the tank and ran away quickly."
Later, in the surveillance room, Assistant Lee said:
"Detective, this confirms the lab report.
The material is high-density PVA, designed to dissolve gradually within ten minutes.
This means the head only became visible after the sphere fully dissolved and the contents floated up… exactly at 18:25 when the first witness entered."
Kim raised his gaze toward the screen, where a high-definition image of the victim Woo Jin's head appeared.
He spoke in a low voice, as if reciting a death ritual:
"Despite the use of a power saw, the cutting paths follow Langer's lines with extreme precision.
This was not mutilation…
it was engineering."
A brief silence fell.
Then he turned halfway and said:
"The killer does not only possess strength…
he possesses knowledge.
We are looking for someone who understands flesh and bone…
a surgeon… or a butcher with the mind of an artist."
He switched the screen to another image.
The message extracted from the victim's mouth was under spectral analysis.
Officer Min asked excitedly:
"Maybe invisible ink? Or hidden symbols inside the paper?"
The lab technician replied in frustration:
"According to the spectral analysis… nothing.
The paper is ordinary, and the ink is commercially available."
The message was completely unencrypted, which made it even more terrifying:
"You have one week… or she will die."
Kim stared at the words:
"He is not trying to hide behind codes…
he wants us to understand that he is not acting randomly."
Then he turned to Assistant Lee:
"Everything is connected to the entertainer Woo Jin.
The woman with the strange fingernail… may be connected to the victim."
Detective Kim lifted his head toward the ceiling and slowly closed his eyes.
As if high-resolution images began to pass through his mind… surveillance cameras… Woo Jin's house… the back alley… the body scene… forensic reports…
He slowly opened his eyes and said:
"The back door of Woo Jin's house opens into a narrow alley.
There are no cameras there.
And the neighboring house owner has been absent for two years.
Search for any camera within a one-kilometer radius.
There may be a woman who frequently visited Woo Jin's house…
she might be the owner of the strange fingernail…
the next victim."
Then he added in a low voice:
"The back door… may reveal what the front door cameras failed to capture."