What Happened at the Seoul Metropolitan Police Agency (2)
At midday, the entrance to Gaeunsan was more deserted than Song Tan had expected.
Since it was a weekday, almost no one was climbing the walking path, and only the soft rustle of leaves swaying in the wind carried through the still air.
“It’s here. This is where the body was found.”
Just off the trail, Do Se-lin pointed at a towering boulder and a single especially tall pine tree.
By then, some time had passed since the incident, so the police line had already been removed.
Song Tan approached and swept his gaze over the surroundings.
“There is a path here, I see.”
“It’s not an official trail. More like a shortcut people wore into the ground.”
“Hmm.”
Nodding, Song Tan brushed at the soil with his fingers, then crouched and examined the grass nearby with careful attention.
“The Forensics Team searched every inch of the area and didn’t find a thing. Not even the usual cigarette butt.”
“No footprints either?”
“Unfortunately not. It rained once after the estimated time of the crime.”
Listening to her explanation, Song Tan looked around again.
The place was farther from the walking path than he’d expected. The dense stand of trees blocked the view. Even the slope was nowhere near steep enough to make escape difficult.
As if measuring something, Song Tan’s gaze moved briskly back and forth.
“The victim was on her way to cram school after finishing classes. Apparently, she often took this route because it was faster.”
“Wait.”
Song Tan raised a hand and slowly closed his eyes.
Do Se-lin, who had been about to say something, fell silent and watched him.
The mountain itself seemed to quiet down.
As the accumulated details stacked together, they began to form a picture in his mind.
The walking path, with the afternoon sun sinking lower and shadows stretching long across it.
A high school girl walking with earbuds in.
Checking the time on her phone, she frowns.
If she wasn’t careful, she might be late.
So she has no choice but to turn onto the shortcut.
Breath coming in short gasps, she hurries her steps.
Then, from behind her, she hears the faint sound of leaves being stepped on.
So faint that someone wearing earbuds wouldn’t be able to hear it at all.
By the time the girl’s figure disappears completely from the viewpoint of the trail, something from behind has already closed the distance in an instant.
One step, two steps, movement so quiet it seems to have swallowed even its own breathing.
A hand reaches out and taps the girl on the shoulder.
When she twists around, a thin, hard blade drives straight toward her chest.
Thud—
The sharp tip of the knife slips between the ribs on the left side of her chest.
A clean thrust. No hesitation whatsoever.
“Ghk!”
The girl’s eyes flew wide as the blade pierced her heart.
In that instant, her breath broke, and no sound could escape her lips.
Her strength drained away at once, and her body collapsed as if folding in on itself.
Her hand clawed at the air, and then the light in her pupils went out.
After that, as though playing some cruel joke, the killer left a few more stab wounds on the body—rough, awkward, and nothing like the first precise blow.
Then, with complete ease, the killer stripped off her clothes and took the cash from her wallet as well.
With a brief glance at the girl, already a cold corpse, the killer vanished without a trace.
Song Tan’s eyes snapped open.
Just then, from far away, the cry of a magpie rang out at the perfect moment.
Do Se-lin came closer and asked cautiously, “Why did you suddenly—?”
“From the moment the knife was driven into the victim’s heart to the moment the killer departed, roughly one minute and thirty seconds passed. The culprit is clearly someone familiar with this terrain. They chose, and chose again, the best possible place to commit murder.”
“What are you talking about right now—”
A hard gust of wind blew through, and leaves came tumbling down in a shower.
Without answering, Song Tan crouched lower until his face was almost level with the ground.
Then, changing angles, he stared at something hidden in the shadows.
More precisely, toward the direction where sunlight slanted in.
At that instant, his eyes flashed with fierce light.
Very faintly, he could see a line pressed beneath the fallen leaves.
It was such a shallow trace it was almost invisible.
“Lucky. It’s still there.”
“What is?”
“The trace left by the culprit.”
“But you just said the footprints were all destroyed—”
Song Tan brushed away the thick layer of leaves and pointed at the damp soil beneath.
Do Se-lin narrowed her eyes.
She tilted her head, then lowered her gaze the way he had and followed the angle of the light. Only then did she see that the earth had been compressed by something, however slightly.
“When it rains, footprints disappear. But soil that’s been weighted down still sinks in place.”
“How did you even—”
Do Se-lin looked at Song Tan with a stunned expression.
She was shocked that he had found a trace even the National Forensic Service had missed.
“Judging by the impressions, the person wasn’t particularly heavy. Even if they were carrying something, we’re looking at roughly fifty-five to sixty-five kilos.”
“That little?”
Song Tan found another impression.
This one didn’t lead toward the walking path, but down the opposite slope instead.
Following the trace, he began moving little by little.
Do Se-lin trailed after him as though spellbound.
“Ordinary people turn their feet outward when going downhill to keep their balance. It’s instinctive. But this impression keeps going in a straight line.”
“So that means…?”
“It means the culprit repeatedly climbed and descended this route. They got used to it.”
“Ah…”
“Let’s keep following it for now. I want to see where it leads.”
“Yes, got it.”
Do Se-lin nodded before she even realized she had.
Her bewildered eyes took in Song Tan’s back.
She had only come here to verify the scene, and never imagined he would find the killer’s trail at all.
What on earth is that man…?
With a foreboding sense that something unusual was about to happen, Do Se-lin’s heart began pounding wildly.
***
It took them an hour to make their way down the mountain, following the dust-fine impressions.
There were no real roads in the forest at all, and they might easily have lost their bearings, but Song Tan kept moving without hesitation.
Gradually, the slope began to ease, and the trees started to stand farther apart.
When the trail of impressions finally vanished, Song Tan came to a stop at last.
“Huff… huff… can we slow down a little?”
Soaked in sweat, Do Se-lin braced her hands on her knees and sucked in ragged breaths.
After catching herself for a moment, she followed Song Tan’s gaze and turned her head.
Ahead was a narrow access road paved with asphalt, and beyond it lay a residential neighborhood sloping down toward Jongam-dong.
“The trail ends here.”
Do Se-lin looked around.
Power lines tangled around utility poles, and old sedans were parked along the roadside shoulder.
She could hear the faint buzz of delivery scooters, but this was still nowhere near a busy area.
Song Tan pointed at the narrow road leading up to the paved street.
“Judging from the last impression, the culprit probably escaped that way.”
The access road was barely wide enough for two people to pass each other.
With a wall on one side and a low retaining structure on the other, it was the sort of place a pedestrian would naturally have to take.
Hope began to rise in Do Se-lin’s eyes.
“Then if there’s CCTV around here—”
“We might be able to identify the suspect.”
Her breathing quickened even more.
“Th-then let’s go check right away.”
Before she even finished speaking, Do Se-lin had already turned on her heel.
The hope that the culprit’s shape, buried in the dark, might finally be brought into the light urged her steps forward.
***
The two of them walked along the access road, scanning the left and right sides as they went.
They circled the alley once, then checked another block before Do Se-lin’s pace began to slow.
“...There isn’t one.”
There was CCTV, but not a single camera directly covered the narrow access road.
“Of all things…”
Deep disappointment colored her voice.
“With these cameras, there’s no way to identify who came out of the access road.”
Without answering, Song Tan walked slowly down the alley.
His gaze darted upward, downward, and sideways.
“I’ll still try to secure the footage. Just in case…”
“Wait.”
Song Tan’s steps stopped abruptly.
His attention was fixed on the end of the alley, on the outer wall of an old laundromat building.
More precisely, on a small CCTV camera mounted beneath the eaves.
“Wouldn’t that angle catch the access road?”
Do Se-lin moved closer, then shook her head.
“The direction’s fine, but it’s mounted too low. The face probably won’t come out clearly.”
“Shall we check it anyway?”
Do Se-lin nodded readily.
After all, if not for Song Tan, they would never have gotten this far.
With the laundromat owner’s cooperation, the two of them began reviewing the footage from just before and after the estimated time of the crime.
The video quality wasn’t good, likely because it was an old model.
Still, the fortunate part was that the entrance to the access road was barely visible on the screen.
Even so, there was a reason Do Se-lin’s expression darkened.
“As expected… it’s only showing legs.”
Only the lower legs of pedestrians crossing the bottom edge of the frame were barely visible.
“There’s no way to identify anyone from this.”
She said it with certainty.
There was no way to recognize a person by their legs alone.
But Song Tan just kept staring intently at the legs in the footage.
One after another, the legs of people exiting the access road passed by.
Jeans, skirts, stockings, black cotton trousers, and more.
Similar-looking legs flickered across the screen one after another.
Then Song Tan’s eyes narrowed further.
“Stop. Rewind a little there.”
The video played again.
“Pause for a second.”
Do Se-lin obeyed immediately.
At the lower edge of the screen, black training pants and black sneakers were caught at the very border of the frame.
Do Se-lin tilted her head.
“Why?”
“That’s the culprit.”
“What!?”
Before she knew it, Do Se-lin had yelped and scrutinized the black pants.
They were ordinary track pants, with an asymmetrical zip pocket on one thigh.
“On what grounds?”
“Remember the impressions. The left stride was subtly shorter, while more body weight was being carried on the right foot.”
“It was…?”
For her, every trace looked the same, so she could only trail off.
“This is the only person whose gait shows the right foot bearing more weight while the left foot follows as if being dragged.”
Do Se-lin narrowed her eyes and kept replaying the video.
At first it looked like an ordinary walk, but after watching it dozens of times, she could finally begin to notice the difference.
The black training pants were moving in a somewhat distinctive way.
Still, the difference was so minor it was hard to pin anything on it.
“If we can find this person in the other CCTV footage, we should get something out of it.”
Do Se-lin nodded.
Now that they had come this far, there was no other choice anyway.
More importantly, Song Tan’s oddly calm presence gave her a strange sense of trust.
She didn’t quite understand why herself.
The two of them immediately began securing CCTV footage from nearby shops and homes, and at last—
“F-found them!”
In one convenience store’s CCTV, the figure in black training clothes finally appeared.
Black from head to toe, even the sneakers and cap.
And there it was, the asymmetrical zip pocket on one leg.
The suspect Song Tan had pointed out.
With a mask on, the face couldn’t be identified.
But one thing was unmistakable.
“A woman…?”
Long hair and a slender build—anyone could tell at a glance she was female.
Do Se-lin muttered under her breath without thinking.
“I didn’t see this coming… If that’s the case, the direction of the investigation was wrong from the start…”
“Let’s keep following her.”
From there, it became a relentless chain of work.
Her figure passing through alleys,
and even the moment she paused briefly in front of a crosswalk.
As they stitched the footage together, the killer’s route grew clearer and clearer.
“I’ll stop here for a moment.”
Do Se-lin froze the screen.
It was a camera looking into the depths of an alley, where a woman in black training clothes could be seen faintly in the distance.
The woman suddenly stopped walking and glanced around.
Then she crouched for a long while in front of a storm drain at the edge of the road, and at some point, she vanished as if into thin air.
The two of them met each other’s eyes at the same time.
“Let’s go.”
***
The alley was exactly as it had appeared on the CCTV footage.
An old house wall, and a metal storm-drain cover at the edge of the road.
It was tucked away in a corner where almost no one would ever look.
Crouching in front of the drain cover, Song Tan placed a hand on the edge.
There was a faint scratch mark there.
Without hesitation, Song Tan lifted the cover.
Squeeeak—
With a heavy grinding sound of metal scraping against metal, the damp, musty smell peculiar to a drain rose into the air.
Song Tan’s eyes glinted as he reached his hand underneath.
And how much time passed after that?
“Ah…!”
Do Se-lin’s eyes flew wide.
More precisely, at the knife in Song Tan’s hand.
The blade wasn’t especially long, but it was narrow, with a slight curve at the tip.
Most decisive of all, the entire blade was covered in dark, hardened stains.
Do Se-lin’s breath caught for a moment.
“The murder weapon…”
“You should probably contact the lead detective right away.”
Do Se-lin hastily pulled out her phone and spoke urgently with someone.
And then, the next day—
News that the prime suspect in the Gaeunsan high school girl murder case had been arrested threw the Seoul Metropolitan Police Agency into an uproar.