1995, Starting as a Criminal Investigation Expert

"We should at least have the ones in the province that have automatic comparison systems."

He Chenghua immediately replied.

The neighboring Yanling, Pingyu, and the provincial capital Ningshan all have AFIS systems.

Especially in Ningshan, which has records of prisoners from the entire province, we definitely need to compare them.

After saying that, he continued counting on his fingers, "There's also Matsuura, Heiju, and even Ankyo. Basically, I think we can try anything that has a comparison system."

Xu Qiang nodded in agreement and said, "Li Shu also said that the fingerprints are of good quality, so let's send letters to those with systematic fingerprints to request a comparison."

There is a system that allows for fast comparisons without much trouble; all you need to do is send a letter of assistance.

But for those without a system, relying entirely on manual comparison, unless you have strong connections, sending letters is unnecessary.

Shao Guiying leaned back in her chair, thought for a while, and said, "I think the taxi case is something we can consider."

Seeing everyone looking at him, he sat up straight.

He continued, "I think it's a very good approach to proactively collect fingerprints in a targeted manner."

"Last year, we screened nearly two hundred suspects, especially those involved in loan sharking, who numbered the most. However, due to limitations, the manpower cost of verification and investigation was too high, so we couldn't screen them thoroughly."

With nearly two hundred suspects, just visiting them once would be a considerable amount of work.

Not to mention verifying their alibis and confirming their whereabouts on the day of the incident.

It was already quite an achievement to verify the identities of so many people back then.

"But it's different now. We have fingerprints, so we can just collect fingerprints. It's not a big deal."

The people present exchanged glances and unanimously agreed.

Li Shu's purposeful and targeted collection of fingerprints, in retrospect, was truly a brilliant move.

Xiao Rui continued, "And it's not just these people, but also their relatives and friends. The suspect's motive for revenge is so strong, there must be some deep-seated hatred."

"Huang Youjun has been lending money at high interest rates for many years. There must have been quite a few people who couldn't repay their debts, were chased by creditors, and ended up with their families ruined. These people, along with their relatives, all had a strong motive for revenge."

"We have his ledger, right? I think we should just follow the ledger and collect data from each and every one of them. I think at most it's only two thousand people."

Xu Qiang on the other side gave a light snort.

"Goodness, quite the boast, 'two thousand at most'? That's two thousand, not two hundred."

Assuming there are indeed that many people, finding just two thousand would not be an easy task.

They also collect fingerprints.

Now it all relies on ink printing, which sounds like an easy thing, but it's not.

When taking a fingerprint, uneven application of ink on the finger, or intentional slipping or squeezing, can cause the fingerprint to become smudged or deformed, affecting the final collection result and rendering the fingerprint unusable.

So you can't just find any policeman and get this done.

Previously, when we went to Madun Bridge to collect fingerprints, the entire fingerprint collection process was handled by the technical team.

Secondly, the collected data needs to be input into the system and stored.

This requires a hard drive.

Li Shu explained that a single fingerprint card input system can take up several megabytes of space.

Two thousand people, that's several gigabytes.

A hard drive is only a few hundred megabytes in size now. Just to store the fingerprints of these two thousand people, we would need to buy several more hard drives, which is no small amount of money.

However, this is indeed a good method.

Xu Qiang pondered for a moment and said, "Send a letter first, compare the results, and if they still don't match, then we'll use this method again."

His judgment was the same as everyone else's: the suspect had a strong motive for revenge and must have some deep-seated hatred for Huang Youjun.

Actually, Xu Qiang and the others didn't even need to mention it.

The next morning, Li Shu approached Han Jianjun and suggested sending his fingerprints to nearby provinces and cities so they could help with the comparison.

"Especially Ningzan and Matsuura."

Because of the Jianhua Hotel case, Matsuura has fingerprint files from eight provinces dating back 81 years.

Huang Youjun is over forty years old, and his enemies are probably around the same age, so it's possible that they had criminal records from over ten years ago.

Next is Ningshan.

As the provincial capital, they have records of all prisoners in the province.

Han Jianjun laughed and said, "I was just about to send a letter anyway. Here's what you do: call 803 and ask them to expedite it."

If it's related, then we have to use it.

After saying that, as Li Shu was about to leave, he called him back and said, "By the way, you don't need to rush with the old case. Take your time. Instead, spend more time thinking about your fingerprint comparison methods and write more papers. It will be good for you."

Previously, Li Shu sent three papers through Zhang Lu, but that wasn't enough.

The surface unfolding system, the extraction of adipocere fingerprints, the application of vacuum coating equipment, and EOS staining agents are all worthy of being written into papers and published.

"OK."

Li Shu nodded.

Speaking of writing, Li Shu remembered the regulations for the preservation of physical evidence and thought about putting pen to paper and writing it down properly.

First, I faxed my fingerprints to 803.

Li Shu called Zhou Xuewen and asked for his help in making a comparison.

Without saying a word, the person called back within an hour, but unfortunately, the match was not found.

Later that day, results also came back from Yanling and Pingyu.

None of them matched.

That leaves Ningshan.

The next day, the results came from the province: the same result, no match found.

That made things complicated.

Apart from Ankyung, Songpu, and Ningjiang, which are wealthy, their investment in police technology is truly among the highest in the country.

In other provinces and cities, even if there are fingerprint comparison systems, they are basically established in the provincial capital with the help of the provincial public security department.

It's just a handful of provinces.

Ningjiang, the provincial capital, Nanjiang, Yanling, and Pingyu are all prefecture-level cities, yet they have them all.

Therefore, if we can't find a match in Ningjiang and Songpu, it will be difficult to make a match across the whole country.

From all over the country.

Fortunately, Li Shu was familiar with Liu Weikun and was able to find out from him which provinces across the country had deployed the system.

After sending letters to Anjing and the other four provinces requesting comparisons, Li Shu could only wait for the results.

Xu Qiang, on the other hand, did not intend to wait idly.

As previously agreed, it was decided to collect fingerprints from Huang Youjun's potential enemies.

"I say, can we use our brains and use some smart methods?" Lin Wanping called out to the group.

Xiao Rui frowned slightly.

That sounds a bit off, so you didn't think beforehand and used a stupid method.

Xu Qiang frowned and said, "Spit it out."

Lin Wanping said, "What I mean is, let's think about it again and see if we can filter it further. Like Li Shu, you see, he was able to analyze that Zhou Pan was related to Madunqiao and was feeling restless, so he wanted to find a prostitute."

"That's the way smart people do it. And what's that old saying? Sharpening your axe won't delay your woodcutting. Just look at those ledgers, so many years, hundreds of people, including family and friends, it's more than two thousand."

Lin Wanping's words were a bit harsh, but the group still listened to his reasoning.

Xu Qiang sat down and retorted, "Then you should use your brain and come up with a screening method."

He also wanted to screen candidates, but the criteria were too few.

There were no witnesses on the day of the incident.

Anyone who witnesses the suspect and knows their height and accent can eliminate a large portion of them.

Lin Wanping chuckled awkwardly, "Isn't it moving?"

Seeing that everyone had sat down, Lin Wanping continued, "Li Shu gave me a book, and now I really think it's quite interesting to study why bad guys are bad."

"So, could we also analyze this from a psychological perspective?"

He asked rhetorically.

The crowd remained silent, lost in thought.

Xu Qiang lit a cigarette, propped his legs up on the table, and let the smoke envelop him as he fell into deep thought.

After thinking about it carefully, he felt that Lin Wanping made a lot of sense.

Collecting fingerprints on a large scale is a really stupid method.

For a moment, Xu Qiang couldn't think of any specific criteria to use for screening.

As I was thinking, an idea suddenly popped into my head.

"I think this mother is very important."

Seeing everyone looking at him, Xu Qiang continued, "You all think that the suspect insisted on doing it at Kang Guiying's house. Could it be that his target wasn't Huang Youjun, or perhaps his target was to make Huang Youjun watch his mother being murdered?"

"So, according to what Lao Lin said, if we analyze the criminal psychology, could it be that the suspect's mother did this on purpose because Huang Youjun died?"

That gives us a selection criterion.