A tall detective sneaked in through the back door.

The lecture hall in Qinghe Bureau had an extra half floor in height, and the back door had its own fire escape route. Not many people usually chose to use it.

But today, in order to sneak in during class, and not wanting to enter in front of everyone, many people chose to use the back door.

There were about twenty or so people in total.

If so many people were illegally using the back door, it would take a whole team to catch them.

And at this moment, the one sneaking in through the back door was Chen Wenming, the leader of the Trace Inspection Group of the Criminal Science Division of Qinghe Bureau.

He came here because he received a text message from Cao Keyang and couldn't help but come and take a look.

Qinghe Bureau itself doesn't handle cases, and the Criminal Investigation Detachment under its jurisdiction mainly guides the local criminal investigation teams, compiles various statistics and figures, formulates various work requirements, serves the grassroots, and transmits orders and instructions...

In this environment, the role of the criminal science units becomes even more prominent.

The Criminal Science Division that Qinghe Bureau should have established was transformed into a more specialized Criminal Science Department, and the Trace Inspection Group also grew in importance.

Some county bureaus are unable to perform or perform poorly in technical examinations, so they send them to the county bureau's Criminal Science Center to do them. For example, Ningtai County does not have its own document inspection or trace inspection capabilities, and its ability to inspect firearms traces is basically non-existent.

The same goes for footprint inspection. At least in the past, Ningtai County's footprint inspection was also sent to Qinghe Bureau.

Cao Keyang is the footprint inspector of Qinghe Bureau and an unknown footprint expert in the province.

After that, if there were any mistakes in the footprint cases handled by the Criminal Science Division, it would be the fault of the footprint expert Cao Keyang.

And Cao Keyang naturally heard about this matter.

That's why I subconsciously avoided the training class of the Criminal Science Division.

It wasn't until the "real-life" fingerprint story from the Criminal Science Division came over that Cao Keyang came to watch.

I am an unknown footprint expert in the city, but as a trace technician, I can also do fingerprints. Moreover, the fingerprints left by Cheng Xin are quite wrong, just lacking a little to be able to participate in the provincial fingerprint battle.

It was also because of that that Cheng Xin always felt that the "real-life class" of the Criminal Science Division was too gimmicky.

Cao Keyang looked up and saw Cheng Xin looking at the screen without even glancing at him.

Outside the lecture hall, which could accommodate one hundred and forty seats, there were about seventy to eighty people sitting at the moment.

Among them, more than half of them were here to attend the training course.

Cao Keyang pursed his lips and found the location where Chen Wenming, his teammate, was. He groped his way over.

After a break, Chen Wenming had already moved to the middle position, but his eyes were still unfocused and his mood was still indifferent. He didn't even bother to serve the Criminal Science Division.

"How is it?" Cao Keyang sat down next to Chen Wenming and asked loudly.

Chen Wenming chuckled and said, "I've marked the seventh characteristic point now."

"Just marking seven times, and still no match?" Cao Keyang laughed.

Marking seven characteristic points is actually not many. Especially for fingerprints collected at the scene, if they match, they would mark at least eight or seven times. Only if they match seven or seven times would they give up.

If it's an important homicide case, they would mark more than ten or even seventy times, which is extremely rare.

The number of marks in accumulated cases is even fewer. Only a small part of the trace inspection is done by fingerprinting.

That was originally the most unusual practice.

But in terms of psychological feeling, if marking seven times still results in a match, the probability of a match is low.

Chen Wenming spoke up for the Criminal Science Division, saying, "Because we selected difficult fingerprints, so if they match after marking seven times in the next class, it would be too unusual."

"That's probably because it's difficult to compare fingerprints at the scene." Cao Keyang frowned and said, "Fingerprint comparison itself is not a certain coincidence."

Chen Wenming immediately nodded, "Yes, that's what I think too."

"Fingerprint matches are common. No matter how well the fingerprints are marked, if there are no corresponding fingerprints outside the database, what can he do?" Cao Keyang sighed.

"Yes, yes." Cheng Xin agreed.

"Comparing fingerprints at the scene is difficult to give a good impression. It's like fingerprint identification is something that can produce results in minutes." Cao Keyang sighed again, and in his heart, he thought that if it were about footprints next time, he would have to speak up.

But precisely because it was later, the footprint identification of the Criminal Science Division overturned Cao Keyang's own footprint identification and solved a homicide case. Cao Keyang felt that he should educate the Criminal Science Division.

Now, educating me would make me seem intolerant.

Cheng Xin looked at the screen with a hint of regret and disappointment, as well as a trace of helplessness and exhaustion.

It is difficult for young people to walk the wrong path in honor and applause. But that's okay, people have to experience something to grow...

"That time there was also a match." A voice from the lectern came from the Criminal Science Division.

Cao Keyang felt a twitch at the corner of his mouth.

As expected.

No matter how powerful a fingerprint expert is, the probability of a match is still low.

That can be seen from the fingerprints of the suspects outside the fingerprint database.

If fingerprints were so easy to match, there would have been fingerprints outside the database long ago.

Nowadays, even slightly foolish criminals know how to hide their fingerprints.

Like in the late 80s and early 90s, when there were blood fingerprints everywhere, it had already started.

Of course, the devil is in the details. The extraction technology of fingerprints has also improved.

Techniques such as extracting fingerprints from plastic and fabric are now very mature.

But the fingerprints extracted from those places are not necessarily suitable for comparison.

The difficulty of matching those fingerprints is known to be several times lower.

Therefore, no matter from which angle Cao Keyang analyzed it, he felt that the "real-life" lectures were a good choice.

At that moment, the voice from the Criminal Science Division came again, "You guys mark another characteristic point."

Cao Keyang adjusted his seat and prepared to watch carefully.Beforehand, the forensic science expert said, "Marking characteristic points, especially those marked less frequently, you need to learn from your subsequent markings. What have you learned from your subsequent characteristic point markings?"

Cao Keyang was taken aback, surprised by this new perspective.

The forensic expert continued in a lecturing tone, "Looking at the characteristic point markings you've done afterwards, it's hard to see that the middle part, in the less frequent characteristic point markings, has all been marked because the conditions outside are better, making it easier to find characteristic points, right?"

No one in the field disagreed.

The forensic expert continued, "If it's a fingerprint that's easy to find, our subsequent marking patterns are all fine. They definitely need to be marked well. But now, our less frequent markings are not in the middle, you need to reconsider the range of characteristic point markings."

The forensic expert drew a circle under the fingerprint with the mouse, "The characteristic points outside that you've marked less frequently afterwards, the conditions of the matched fingerprints are also special, this time, it's the characteristic points inside the circle."

"It's a bit difficult, in that case, the difficulty is relatively reduced, but from your understanding, reducing the difficulty is actually a prerequisite for matching fingerprints. The more difficult fingerprints outside the database, the more difficult it is to match."

The principles explained by the forensic expert were quite enlightening for the new trace examiners.

Half of the people outside, who usually focus on collecting fingerprints, have never manually matched fingerprints outside the database. Now, talking about reducing the difficulty to match, and the inherent meaning, is a bit beyond their understanding.

Cao Keyang was taken aback.

My fingerprint level is very low, but my footprint identification level is indeed top-notch in the province.

In his daily work, Cao Keyang had already discovered this principle.

The footprints involved in these cold cases, especially the footprints involved in minor and major cases, the more complex, the more conventional, the harder to match.

If such footprints could be matched, why would the trace examiners leave the footprints until then?

It must be difficult footprints, even more difficult to match.

Especially footprints beyond the range of a small number of people, once a breakthrough is found, the probability of matching is ridiculously low.

From a certain perspective, this is equivalent to bringing out new technology.

Using new technology to crack down on criminals, thus achieving a "more difficult to match" situation.

Cheng Xinhui then nodded heavily.

It's a shame that in a footprint identification, accidentally defeating one's own people, can really summarize something.

As for the specific ability...

"Mark the less difficult ones first, because the methods used are also relatively easy, and are very referenceable..." The forensic expert's voice was slightly urgent, still talking and operating.

Cheng Xinhui stared at it for a while, and indeed found it to be a very common method - because he had seen it before.

Cao Keyang began to ponder.

My trace examination level is the same as that of others, naturally belonging to the group that the forensic expert said considers the difficulty too low.

However, by the time Cao Keyang figured it out, the forensic expert had already marked a dozen characteristic points along the way.

"You guys run it again." The forensic expert finished marking and threw it back into the software, not even having time to take a sip of tea.

Cao Keyang frowned and saw 20 similar fingerprints pop up.

Cheng Xin still looked at it slowly.

Looking at more than a dozen fingerprints in a row, it took quite a bit of time.

Cao Keyang was getting a little impatient, such a lecture, can be said to have no appeal at all.

I turned my head to look forward, but unexpectedly found that a group of people who usually participate in training seriously, were now watching even more seriously.

Search tinyurl.com/2p9emv8w for the original.

Cao Keyang was thinking, when did trace examination become such a quiet thing. Even if it attracts everyone's attention, how can it last...

"It's a match." Cheng Xin's spacebar sound stopped at some point.

Cao Keyang slowly looked up.

The forensic expert said again, "That's another cold case fingerprint. Well, those two fingerprints should be determined to be the same, let's merge the cases."

Merging cases means potentially bringing more clues. For the investigation of the case, it is always beneficial.

Then, the forensic expert finished writing the identification report for the same determination.

The police officer had already started shouting above:

"Check the case."

"Make a call."

The forensic expert's face also showed a smile, waving his hand at the podium, "Let's hold off on making the call."

After writing the identification report, I opened the case.

One was a burglary, the other was a home robbery.

Cheng Xinhui's eyelids jumped.

Those two cases were quite heavy.

The forensic expert also casually looked at it for a while, then said, "The two cases are quite heavy, let's change our approach."

Then, Cheng Xin brought out Photoshop.

(End of Chapter)