Diary of a Criminal Investigator

"Any other clues?"

Wang Song shook his head, "Basically none. The crime scene was deep in the mountains, the corpse had been gnawed by wild animals, leaving no traces."

"If it weren't for hikers entering the mountains and accidentally discovering the body, we wouldn't have found it."

Compared to death, a missing person case is the hardest to deal with.

When someone dies, at least you know they're dead.

When missing, no one knows what really happened.

The fingerprints extracted from Zheng Bin's field dagger weren't just blurry.

After magnifying the fingerprints, Lu Chuan clearly identified them as composite fingerprints layered upon each other.

There were also traces of blood, and faintly discernible, incomplete wiping marks.

"After using the dagger, the murderer must have wiped the fingerprints off the handle with something."

Wang Song nodded, "Yes, that's what the experts at the provincial department said back then."

"But they weren't meticulous enough when reprocessing, still leaving some residual scratched fingerprints."

In plain terms, such fingerprints are the result of a slip of the hand.

Moreover, after wiping the handle, the murderer likely covered it with another layer of fingerprints.

No doubt, the murderer must have handed the dagger back to Zheng Bin.

Not surprising that Wang Song kept nodding while listening, "Yes, yes, the experts at the provincial department said the same thing."

Lu Chuan nodded. He could discern these details, even when he only had intermediate fingerprint identification and analysis skills.

However, at that time, he didn't have the ability to conduct fingerprint identification analysis.

"Brother Wang, please wait a moment, this might take me a while."

This fingerprint processing clearly wasn't something that could be completed in a short time.

This was, to date, the most challenging fingerprint analysis Lu Chuan had faced.

Lu Chuan couldn't guarantee its eventual success.

First, the fingerprint had to be digitized, using two-dimensional transformation to complete data layering.

Compared to the naked eye's view of stacked fingerprint ridges, the layered data of the fingerprint image makes it easier to process.

This was easier said than done when dealing with it.

Lu Chuan manually filtered the data, which alone took over an hour.

The meeting room was eerily silent.

Besides Lu Chuan's typing, no one else made a sound.

Zheng Bin's murder case, though it had been nine years, remained unresolved.

Was he killed because of the cases in his hand, or did he encounter something fatal in the mountains?

Moreover, since he died while on vacation, his death was not even classified as a work-related death.

Let alone considered a sacrifice.

Without considering his police status, it was a simple murder case, lacking clues.

Therefore, even back then, the investigation on this case wasn't as resourceful as Song Kun's murder.

It was hard for Zheng Bin's wife, who had just become pregnant at the time.

And for the son who lost his father before he was even born.

In recent years, Zheng Bin's wife never remarried; the Water District Criminal Investigation Team arranged an internal assistant job for her as a kind of indirect help.

Once the fingerprint was layered, the real work began.

Because the fingerprint had scratches and had been wiped by the murderer, the beginning and end points had no reference fingerprint lines.

Lu Chuan had to convert the multiple long friction lines back into a fingerprint shape.

No one disturbed Lu Chuan all afternoon.

When Gao Wenxiang and the others smoked, they focused their conversation on Lu Chuan's forensic fingerprint analysis: "Old Sun, you're the best in this group, do you think there's a chance?"

Sun Hao exhaled a puff of smoke, "I reviewed Zheng Bin's case back then too."

"With that fingerprint, it wasn't just me. Even the experts at the provincial department couldn't crack it after studying it for over ten days."

"Lu Chuan..."

Others sighed along.

Clearly, although everyone knew Lu Chuan was skilled, far surpassing them, being able to solve two unresolved murder cases at the provincial department level was certainly impressive.

This showed Lu Chuan had already reached the level of a top provincial fingerprint expert.

But even so, the experts at the provincial department hadn't cracked that fingerprint back then.

As everyone smoked, Lu Chuan's preprocessing of the fingerprints reached its most crucial stage.

Wang Song sat beside Lu Chuan the whole time, observing Lu Chuan extracting the fingerprint bit by bit.

Despite closely watching Lu Chuan's operations, Wang Song understood little.

If he had to describe it, it would be 'unknowingly impressive.'

"Finally, it's about done!"

At 4:28 PM.

After a four-hour battle, the blurred fingerprint had finally transformed in Lu Chuan's hands into a third of a clear, normally extended fingerprint.

Next, he just needed to mark the feature points, calculate some data, and compare it in the system.

After much hard work, a final step.

"Will it work?"

Wang Song seemed more nervous than Lu Chuan, beads of sweat forming on his forehead.

Lu Chuan smiled wryly, "This fingerprint is too severely damaged, and the degree of deformation makes the original fingerprint unrecognizable."

"I used a probability analysis method to deduce the most likely extension of the fingerprint; whether it will work… no one can say for sure."

"Let's run it in the system, we can have a cigarette."

Wang Song watched as Lu Chuan dragged the fingerprint into the system's comparison interface before getting up to join Lu Chuan in the outside smoking room.

At 4:30, the sky was already dark.

Yet the detectives participating in the fingerprint battle hadn't left; they were all waiting for Lu Chuan's fingerprint analysis result.

"All done?"

In the smoking room, everyone was there. Seeing Lu Chuan and Wang Song come out, Gao Wenxiang quickly asked.

"The system is processing it, let's have a smoke."

In truth, everyone hoped Lu Chuan would join them for a smoke.

After all, the flavor of Zhonghua cigarettes was indeed far superior to Hongmei.

As usual, Lu Chuan handed out cigarettes to everyone, lighting one for himself.

Though Lu Chuan wasn't addicted to smoking, as his father had said, cigarettes were the best social tool among men.

With them, came shared topics of conversation.

"How's Director Wang doing?"

That afternoon, Lu Chuan had been focused on fingerprint analysis and hadn't inquired about the two cases from the morning.

He casually asked.

"Ha ha, we were just talking about that."

Sun Miao leaned over, "Director Wang just got back not long ago, the two cases you worked on this morning have been solved; the culprits were caught."

"I heard they barely needed to be interrogated; they came clean on the way back."

Perhaps feeling somewhat closer due to sitting next to Lu Chuan that morning, Gao Wenxiang remarked, "I just heard that Director Song said after this fingerprint battle ends, you'll definitely receive a second-class merit award!"

Second-class merit award!

Upon hearing this, everyone participating in the battle had varied expressions.

Earning merit is something everyone desires.

Not only is there honor, but also monetary rewards.

But solving two unresolved murder cases in one go isn't something just anyone can achieve.

Just the outcome of this fingerprint battle by the Haizhou City Public Security Bureau, not to mention the remaining six days, solving two long-standing murder cases would be considered a major accomplishment even at the provincial level.

And given that Lu Chuan solved these cases almost single-handedly, a second-class merit award is not excessive.

Of course, a first-class merit award is unlikely.

Unless Lu Chuan resolved half of the thirteen murder cases, then that would be more likely.

As they chatted, Wang Song took two deep drags on his nearly burnt-out Zhonghua cigarette and extinguished the butt in the nearby column-style ashtray, "You guys chat, I'm going back to check the comparison results."