Chapter 169: Looking at the Case

The Qinghe Bureau's small lecture hall was located on the first floor of the office building.

The green plants inside were a bit withered, but no one cared.

It, along with other unimportant departments, kept its doors open, welcoming guests from all directions. This included members of the public who didn't know the truth, as well as police officers from various places who didn't know the truth.

However, the utilization rate of the small lecture hall was still very high.

As an administrative bureau that was formalistic, the Qinghe Bureau attached great importance to the organization and reporting of various activities. Otherwise, its existence would be too meaningless.

Today, the small lecture hall was also sitting with quite a few people, and then a tall young man was lecturing slowly, as if he were a college student giving a speech on stage.

It was just that the atmosphere was quite different.

The young police officer wore gray shoulder straps, which meant he was a technical police officer. Wearing a full set of police uniforms, he looked very good. Although he didn't look like the currently popular traffic-star types, he could be considered a gentle and sunny big boy, and with the bonus of the uniform, sitting in the lecturer's seat, with a serious expression, waving freely, it seemed like he could be used for publicity just by taking a random photo.

Jiang Yuan also wore a pair of non-prescription glasses for this training. He wasn't actually nearsighted, but he looked young, and his master said wearing glasses would be better.

And the group of police officers sitting in the viewing seats looked nervous and solemn, looking at the projection screen, their cheek muscles clearly twitching slightly, and their eyes were wide open, very forcefully.

The 20 approximate fingerprints matched in the first pass were listed on the right side of the screen in a vertical row.

The three-quarters on the left displayed the one with the highest value among the approximate fingerprints completely.

"Um, let's look at the fingerprints returned in the first pass."

Jiang Yuan pushed his unfamiliar glasses frame with one hand, grabbed the mouse with the other, clicked, and enlarged the fingerprint on the left to the full screen.

And the fingerprint displayed synchronously on the projection screen was also relatively clear.

"Um, there is an exclusion point here." Jiang Yuan clicked twice, enlarged the fingerprint again, and then his mouse drew a small circle on the right side of the fingerprint to show everyone.

For fingerprints that have already been matched, the standard executed is not how many feature points are consistent, but whether there are any inconsistent feature points.

This is easy to understand. If two fingerprints are the same, then theoretically, all their feature points should be the same.

Therefore, if two fingerprints have one inconsistent feature point, it can be determined as "excluded."

That is to say, the two fingerprints are not the same; they are not the same fingerprint.

Following this train of thought, Jiang Yuan eliminated two approximate fingerprints in a row.

At this time, Cao Keyang of the Qinghe City Bureau, who was sitting in the front row below, said: "Teacher Jiang, shouldn't we put the two fingerprints out for comparison? Excluding them directly like this makes it unclear for everyone to see."

Jiang Yuan reacted quickly, immediately clicked twice, and let the original fingerprint and the matched fingerprint appear on the left three-quarters of the screen at the same time.

"Sorry, I was thinking that the first few fingerprints could be done faster." Jiang Yuan said sincerely.

A hint of sourness inexplicably rose in Cao Keyang's heart, and he hurriedly said: "It's fine, this isn't your problem. It's just to say, we are lecturing, it's better to lecture a bit slower and clearer."

"Mm, I'll pay attention." Jiang Yuan nodded and said again: "Then let's re-exclude the first two fingerprints."

Then, Jiang Yuan used the exact same action to draw a circle on the right.

What was different was that he subsequently drew a circle on the left as well.

Thus, the audience below finally let out a continuous sound of "Oh."

Seeing this, Jiang Yuan struck while the iron was hot, circling the second and third fingerprints as well, before moving on to the next.

The "ohs" and "ahs" from the audience gradually died down.

Technicians with fingerprint skills below LV1 began to feel a sense of bitterness in their hearts—a sour, astringent, indescribable feeling.

They finally understood that Jiang Yuan had actually memorized the entire set of original, difficult fingerprints.

So, the elimination method he used just now was purely based on memory.

Without needing to compare them, having the original patterns in his mind made the process of elimination or matching naturally very fast.

This wasn't actually anything special.

If everyone had started preparing for the lesson days ago, given enough time, everyone would be able to memorize... parts of the fingerprints, at least.

The key was, who would actually do that?

With such intricate fingerprints, no one would expect them to be memorized.

Even the fingerprints themselves would probably feel annoyed.

It is true that some trace evidence examiners, after years of focusing on a specific difficult fingerprint, will gradually memorize its characteristics, but... but...

While some people were lost in their own thoughts, Jiang Yuan had already eliminated three more similar fingerprints.

Then, they heard Jiang Yuan say: "At this point, it is generally recommended to look through all 20 fingerprints. But we won't look at the rest today, because the similarity of the fingerprints appearing is getting lower and lower, which means the probability of a match further down is already very low..."

Cao Keyang was stunned.

The crowd was stunned.

Why did this feeling seem so familiar?

It was just like when he was still in school; he would lower his head to pick up a pencil, and when he looked back up, he could no longer understand what the teacher was saying.

Even the final words were the same: "I won't write out the following steps because they are relatively simple, so we'll skip them, but the conclusion that can be drawn from this is..."

Jiang Yuan had no intention of pausing.

After the first wave of fingerprint screening, Jiang Yuan pulled up the original fingerprint again and said, "We are now marking the feature points for the second time."

Dazzling,

A chaotic blur to the eyes,

Out of sight, out of mind,

It's useless to be annoyed,

After this operation, Jiang Yuan had once again completed the marking of thirteen feature points.

Jiang Yuan said: "The positions we just marked are relatively common feature points. There was no match, which means the previous trace evidence examiner did a decent job with the basic work; the criminal suspect did not leave a very clear full fingerprint for us to match. It doesn't matter, let's try again."

Following steps similar to the ones just now, Jiang Yuan threw the marked fingerprint into the database for comparison.

A moment later, the data returned by the fingerprint database was another column of 20 fingerprints.

"We still need to compare them side-by-side, right?" Jiang Yuan asked Cao Keyang this time, just to be polite.

Cao Keyang nodded obediently, focusing his mind as he watched the projector.

This time, he felt he should be prepared.

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

Jiang Yuan's mouse moved lightly, drawing a small circle on the left and a small circle on the right, saying: "Eliminated, right? It's pretty much the same idea as before."

"The second one is also eliminated."

"Same here."

"For the ones further down, we don't need to circle them one by one, right?"

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

Every time he tapped the spacebar on the keyboard, a new fingerprint would appear on the screen, replacing the old one.

Since Jiang Yuan no longer needed to draw circles, he would just take one look, say "Not it," and then tap the spacebar again to load a new fingerprint.

Cao Keyang started off staring intently, but soon fell back into the same state as before:

Eyes

Chaotic

Eyes

Annoyed

For a moment, Cao Keyang almost thought he was scrolling through short videos.

The screen was full of internet-famous young ladies, and they all looked quite similar.

Take a look, swipe away.

Look at another one, swipe away again.

In a daze, half an hour passed by.

At this point, Jiang Yuan had also re-marked the fourth wave of feature points and said: "Actually, the feature points we marked just now weren't strictly necessary; it was just to demonstrate for everyone."

"In the future, when you have the opportunity and have practiced enough, you can omit the marking mode we just used, because the feature points marked just now overlapped with the previous two times. If it's just for the sake of trying, this method is not very efficient."

"A more efficient way is actually to define a small area and then mark as many feature points as possible; this way, the accuracy of the feedback from the fingerprint will also improve. Of course, the difficulty will also be a bit higher."

"Still using the same method as before..."

As Jiang Yuan spoke, the sound of tapping spacebars echoed through the lecture hall.

It wasn't just Cao Keyang; most of the technicians in the lecture hall had become somewhat numb.

Jiang Yuan was doing it too fast.

Everyone was having trouble keeping up.

Yet they hadn't considered that if Jiang Yuan followed their speed, explaining while doing the fingerprint analysis, wouldn't a single difficult fingerprint take days to finish?

The total time for a training session was only two lessons, totaling 4 hours.

An older trace evidence examiner cleared his throat at this moment, which likely meant he wanted to speak.

Everyone held their breath, waiting for this brave big brother to speak up for them.

After all, this was training within a disciplined force; if they annoyed the teacher, it would be very easy to get into trouble.

The tapping sound suddenly stopped.

For nearly half a minute, Jiang Yuan didn't speak or move.

The lecture hall was so quiet that Cao Keyang, who had already given up, couldn't help but look up at the projection screen.

On the projection screen, there were still two fingerprints.

The original fingerprint on the left, with its status as a difficult fingerprint, looked like a young lady in tight-fitting pants—it looked like she was barely covered, yet she wasn't revealing anything at all.

The fingerprint from the database on the right was ordinary, like an icy, professional-looking woman in a business suit—her gaze was sharp, her movements were dismissive, and there wasn't a single flaw on her from head to toe...

"It's a match, right?" Jiang Yuan added a sentence afterward, which could be considered part of the lecture.

Cao Keyang was completely stunned. What did "it's a match" mean?

He looked at the original fingerprint on the left, then looked at the fingerprint from the database on the right.

They seemed quite similar.

Almost identical.

No flaws.

Impossible to eliminate.

Then... didn't that mean he had to certify them as the same?

In the end, the beauty in tight pants and the icy professional woman were the same person?

Cao Keyang's mind went blank.

It wasn't just Cao Keyang; half of the police officers receiving training in the room were in a daze.

At this moment, Jiang Yuan began to skillfully draft the "Same Identity" appraisal report and applied for a review.

Forty-some people in the room just watched Jiang Yuan filling out the form by himself.

Everyone understood the form-filling part.

"Wait a moment for the review here; I need to find the phone number for the jurisdiction here." As Jiang Yuan spoke, he said to the students: "Sorry for taking two minutes of everyone's time; after all, since the criminal suspect has been locked in, it's more polite to make a phone call."

"No problem, no problem." A group of police officers waved their hands, feeling restless.

Jiang Yuan then switched back to the case details, found the information for the local police station, and smiled: "It's Miaohe County. I've spoken to them on the phone before; wait a moment."

Jiang Yuan had matched a fingerprint from a cold case homicide in Miaohe County during a province-wide fingerprint battle, so he still had the phone number of the captain of the Miaohe County Criminal Investigation Brigade.

Jiang Yuan dialed the number, and soon, he heard the cheerful voice of the Miaohe County Criminal Investigation Brigade captain: "Forensic Doctor Jiang, what brings you to call me? Is it good news?"

"I just matched a regular case, a robbery case from over six years ago... Yes, I'll send the specific information to your internal network. That's right, that's right. Oh... the review has passed... You're welcome, you're welcome."

Jiang Yuan was sitting at the lecturer's podium, and the sound pickup was excellent; the conversation on both mobile phones fell into everyone's ears.

The technicians present were all in a trance.

The Miaohe County Criminal Investigation Brigade captain's temper was actually this good?

Could someone with such a good temper really be a criminal investigation brigade captain?

Besides, what had just happened?

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

"Alright, the review has passed, so this cold robbery case from six years ago can be considered to have a new key lead. Next, it's up to Miaohe County to locate and arrest the criminal suspect. For us, the fingerprint comparison work for the case just now is considered complete."

Jiang Yuan clicked off the few pages he had just opened, completing the final organization work.

"Let's find another typical fingerprint and repeat the method we just used to see if it's feasible." Jiang Yuan started searching for fingerprints again.

The guy who had been clearing his throat just now finally couldn't hold it in anymore. He stood up with a "whoosh," but what he wanted to say had completely changed: "Just now, was that a real case we were working on?"

"Yes." Jiang Yuan replied, then added: "That's why I said it's a practical lecture. Um... regarding the content I said and my teaching style, can you get used to it?"

"Yes, yes, yes, but, no, we... no, you... no, you just solved a robbery case?" The guy who had been clearing his throat was probably unable to accept this.

Soon, the small lecture hall was buzzing with noise.

Some people were even quietly sending messages: Brothers, come quickly to see a god.