Chapter 169: Reviewing the Case

The small lecture hall of the Qinghe Bureau is on the first floor of the office building.

The indoor greenery is slightly withered, but no one cares.

It, along with other unimportant departments, keeps its doors wide open, welcoming visitors from all directions—uninformed civilians and police officers from various regions who are equally clueless.

Yet, the utilization rate of this small lecture hall remains very high.

As a theoretical bureau, Qinghe Bureau places great emphasis on organizing and reporting various activities; otherwise, its existence would be utterly meaningless.

Today, the lecture hall is filled with quite a few people, and a tall young man is slowly delivering a lecture, as if giving a university speech.

But the atmosphere is quite different.

The young police officer wears gray shoulder insignia—he's a technical officer—dressed in a full uniform that looks sharp. Though he doesn't resemble today's popular idol stars, he's a clean-cut, sunny young man, and the uniform adds to his appeal. Sitting at the podium, his expression is serious, his movements natural, and any photo taken of him could easily serve as promotional material.

Jiang Yuan also wore non-prescription glasses for this training—he has no nearsightedness—but his mentor said wearing glasses would make him look more mature.

Meanwhile, the officers seated in the audience stared intently at the projection screen, their facial muscles visibly twitching, eyes wide open with intense focus.

The first round of twenty similar fingerprints appeared in a vertical column on the right side of the screen.

The left three-quarters displayed the fingerprint with the highest similarity score, fully enlarged.

"Alright, let's look at the first round of returned fingerprints."

Jiang Yuan pushed his unfamiliar glasses up with one hand, gripped the mouse with the other, clicked once, and zoomed the left fingerprint to fill the entire screen.

The fingerprint displayed on the projection screen was also quite clear.

"Hmm, here's an exclusion point." Jiang Yuan clicked twice, zoomed in further, then drew a small circle with his mouse on the right side of the fingerprint, signaling to everyone.

For fingerprints already matched, the standard isn't how many feature points match—it's whether any feature points differ.

This is easy to understand: if two fingerprints are identical, theoretically, all their feature points should be identical.

So if even one feature point differs between two fingerprints, you can rule them out.

That means the two fingerprints are not the same.

Following this logic, Jiang Yuan eliminated two similar fingerprints in quick succession.

At this point, Cao Keyang from the Qinghe City Bureau, seated in the front row below, said: "Teacher Jiang, shouldn't we display both fingerprints side by side for comparison? Eliminating them directly makes it hard for everyone to see clearly."

Jiang Yuan reacted instantly, clicking twice to display both the original fingerprint and the matched one simultaneously in the left three-quarters of the screen.

"Sorry, I thought we could move faster through the first few fingerprints," Jiang Yuan said sincerely.

Cao Keyang felt an inexplicable pang of bitterness and quickly replied: "No problem, it's not your fault—just, since this is a lecture, it'd be better to go slower and clearer."

"Mm, noted," Jiang Yuan nodded. "Let's re-examine the first two fingerprints."

Then, Jiang Yuan performed the exact same motion, drawing a circle on the right.

This time, however, he also drew a circle on the left.

Finally, the audience let out a continuous chorus of "Oh!"

Seeing this, Jiang Yuan pressed on, circling the second and third fingerprints as well, eliminating them one by one.

The audience's "Ohhs" gradually faded.

Technicians with fingerprint proficiency below LV1 began to feel a strange bitterness—a dull, indescribable ache.

They finally realized Jiang Yuan had memorized the entire original difficult fingerprint.

So earlier, he'd eliminated matches purely from memory.

Without needing to compare, having the original image in his mind made elimination or matching incredibly fast.

That's not unusual.

If you'd started preparing days ago and spent enough time, everyone could memorize parts of the fingerprint…

But who would actually do that?

Such intricate fingerprints—nobody expects anyone to memorize them.

Even the fingerprints themselves would get tired of it.

Only trace examiners who've spent years focusing on a single difficult fingerprint gradually memorize its features—but then again…

While some were lost in thought, Jiang Yuan eliminated three more similar fingerprints.

Then Jiang Yuan said: "At this point, it's usually recommended to review all twenty fingerprints. But today, we won't. The similarity scores are dropping sharply, meaning the chance of further matches is extremely low…"

Cao Keyang froze.

The audience froze.

Why did this feel so familiar?

Like back in school, when you bent down to pick up a pencil, then looked up and couldn't understand the teacher anymore.

Even the final words were identical: "I won't write out the next steps—they're simple, so we'll skip them—but the conclusion we can draw is…"

Jiang Yuan showed no intention to pause.

After eliminating the first batch of fingerprints, Jiang Yuan pulled up the original fingerprint again. "Now, let's mark the fourth round of feature points."

Blurred vision,

dazzling patterns,

out of sight, out of mind,

even if annoyed, it's useless—

after this flurry of operations, Jiang Yuan completed thirteen new markings.

Jiang Yuan said: "The positions we just marked are common feature points that didn't match. This shows the previous trace examiner did a decent job—the suspect didn't leave a clear, complete fingerprint for us to match. No problem—we'll try again."

Similar to before, Jiang Yuan submitted the marked fingerprint to the database for comparison.

Soon, the database returned another vertical column of twenty fingerprints.

"We still need to compare left and right, right?" Jiang Yuan asked Cao Keyang politely.

Cao Keyang nodded obediently, eyes fixed on the projector with focused stillness.

This time, he felt he was finally prepared.

On the left three-quarters of the projector screen, two fingerprints appeared.

Jiang Yuan's mouse moved lightly, circling a small area on the left, then another on the right. "Excluded, right? Same as before."

"Second one excluded."

"Same thing."

"For the rest, we don't need to circle each one individually."

As he spoke, Jiang Yuan rapidly scrolled through the fingerprints.

Each time he pressed the spacebar, a new fingerprint replaced the previous one on screen.

Since he no longer circled, he simply glanced, said "No," then pressed space again to bring up the next.

Cao Keyang stared at first, then quickly fell back into his earlier state:

eyes

confused

eyes

annoyed

For a moment, Cao Keyang felt like he was scrolling through short videos.

The screen was filled with internet-famous girls, all looking nearly identical.

Look once, swipe away.

Look again, swipe away again.

Dazed and half-asleep, half an hour passed.

At this point, Jiang Yuan had finished marking the fourth round of feature points. "Actually, the feature points we just marked weren't necessary—they were just for demonstration."

"Once you've practiced enough, you can skip this marking pattern entirely, because these points overlap with the previous two rounds. If you're just experimenting, this method is inefficient."

"A more efficient approach is to define a small region and mark as many feature points as possible—this improves the accuracy of returned matches, though it's harder."

"Still, the old method…"

As Jiang Yuan spoke, the lecture hall filled with the rapid, rhythmic sound of spacebar taps.

Not just Cao Keyang—most of the technicians in the room were numb.

Jiang Yuan moved too fast.

Everyone was struggling to keep up.

Yet none of them considered: if Jiang Yuan worked at their pace, explaining and marking each difficult fingerprint step by step, wouldn't it take days to finish one?

A single training session is only two 2-hour blocks.

Some older trace examiners cleared their throats—clearly wanting to speak.

Everyone held their breath, waiting for this brave soul to voice their thoughts.

After all, this was a disciplinary unit's training—if the instructor got upset, you'd easily get punished.

The rapid tapping suddenly stopped.

For nearly half a minute, Jiang Yuan said nothing, made no move.

The lecture hall fell so silent that Cao Keyang, who'd nearly given up, unconsciously lifted his gaze to the screen.

The screen still showed two fingerprints.

On the left: the original difficult fingerprint, like a woman in a tight skirt—seemingly barely clothed, yet revealing nothing.

On the right: a fingerprint from the database, ordinary, like a frosty executive in a sharp suit—cold-eyed, rejecting, with not a single flaw.

"Matched, right?" Jiang Yuan added, as if part of the lecture.

Cao Keyang was utterly stunned. What does "matched" mean?

He looked at the latent fingerprint on the left, then at the fingerprint in the database on the right.

It looks pretty similar.

Nearly identical.

No discrepancies.

Cannot be ruled out.

Then… doesn't that mean we have to confirm they're the same?

So in the end, the curvy beauty and the icy beauty are the same person?

Cao Keyang's team was stunned into silence.

Not just Cao Keyang—half the police officers in the room undergoing training were frozen in shock.

At this point, Jiang Yuan began skillfully drafting the "Identity Confirmation" report and applied for review.

In a room of over forty people, only Jiang Yuan was filling out forms.

Everyone understood the form-filling part.

"Just wait a moment for the review—I'll find a phone number for this jurisdiction," Jiang Yuan said, then added to the trainees: "Sorry to hold you up for two minutes; since we've identified the suspect, it's polite to make a call."

"No problem, no problem," a group of police officers waved their hands nervously.

Jiang Yuan switched back to the case details, located the jurisdictional police station's information, and smiled: "It's Miaohe County. I've called them before—just a moment."

Jiang Yuan had matched a fingerprint from a cold case in Miaohe County during the provincial fingerprint campaign, so he had saved the phone number of Miaohe County's Criminal Investigation Brigade captain.

Jiang Yuan dialed the number, and soon, the captain of Miaohe County's Criminal Investigation Brigade chuckled over the line: "Dr. Jiang, what brings you calling me? Good news?"

"I just matched a routine case—a robbery from over six years ago… yes, I'll send you the specific details via the internal network. That's right, right… oh, the review's been approved… no need to thank me, no need at all."

Jiang Yuan sat at the lectern, and the microphone picked up clearly—the entire conversation between the two men reached everyone's ears.

The technicians in the room were all dazed.

Could the captain of Miaohe County's Criminal Investigation Brigade really be this nice?

Could someone this easygoing even be a Criminal Investigation Brigade captain?

And what exactly just happened?

In the eerie silence, Jiang Yuan completed the step of sending the information via the internal network.

"Alright, the review is approved. So this six-year-old robbery cold case now has a new critical lead. Next, we'll see if Miaohe County can locate and apprehend the suspect. For us, the fingerprint comparison work on this case is complete."

Jiang Yuan closed the several pages he had just opened, finishing the final cleanup.

"Let's find another typical fingerprint and try repeating the method we just used—see if it's viable," Jiang Yuan said, searching through fingerprints again.

The guy who had been clearing his throat earlier finally couldn't hold back—he stood up with a loud "whoosh," but what he meant to say had completely changed: "Wait—was what we just did an actual case?"

"Yes," Jiang Yuan replied. "That's why this is practical training. By the way… are you able to adapt to my content and teaching style?"

"Yes yes yes, but wait—we… no, you… not you, sir… did you just solve a robbery case?" The guy clearing his throat couldn't accept it.

Soon, the small lecture hall was filled with loud chatter.

Someone even quietly sent a message: Brother, come quick—there's a god here.