Chapter 135: Advanced

Late night.

Even the owls were asleep.

After hearing Jiang Yuan's words, the technical staff regained some motivation.

In the scavenger's courtyard, just inside the entrance, several technicians gathered, standing behind Jiang Yuan, listening to him while observing the bloodstains on the ground.

Under the bright lights, the color of the blood appeared distorted, yet its cruelty was still faintly perceptible.

Jiang Yuan's finger pointed to a rare spot on the ground unobstructed by objects—several blood spots stood out clearly.

"I don't see any spatter patterns here either," Hou Xiaoyong said. He had studied bloodstain analysis, but only knew basic, commonly known facts.

Jiang Yuan merely nodded slightly and said, "Books say spatter patterns usually indicate the primary crime scene—the initial point of attack. But here, the weapon's lethality is clearly insufficient, suggesting the killer's original intent may not have been murder."

Jiang Yuan compared the height to his own head and added, "From the cast-off patterns around, you can tell the weapon was blunt. And look at the speed of these cast-off stains—notice it more clearly on this wall."

Everyone gathered to examine the bloodstains on the wall.

The wall, built of red bricks and cement, was covered mostly with oval and elongated stains, with finer droplets ahead.

"This is characteristic of relatively high-velocity stains, meaning the blunt instrument wasn't heavy—likely long," Jiang Yuan analyzed as he observed.

Several technicians nodded along, acknowledging these well-known facts.

"So his first strike probably didn't bleed, and produced no spatter," Jiang Yuan glanced at Hou Xiaoyong, answering his question.

Hou Xiaoyong slowly nodded in agreement.

Indeed, if you hit someone on the forehead with a blunt object, it doesn't immediately bleed.

"But after being struck, Zhang Hong—the dead scavenger—made evasive movements. The blood on this handprint was pressed on afterward, showing he lunged forward," Jiang Yuan pointed ahead and said, "The cast-off stains here indicate the second blow broke the scalp."

Jiang Yuan took two more steps forward; before him lay a pile of collapsed objects.

"This is the mark from the seventh strike. Photograph it first—collect the blood evidence now. The rest can be set aside for later," Jiang Yuan gestured with his hand, defining a section.

Hou Xiaoyong and the others, who had been learning crime scene reconstruction from Jiang Yuan, froze, bewildered.

"You ask."

"You ask."

Several technicians exchanged glances.

The senior technician, exhausted from the back-and-forth glances, finally shot them a furious stare: "Are you going to ask or not? If you won't, I'm done. Why pretend now? When someone asks you later, who'll answer?"

Hou Xiaoyong sighed and spoke up: "Forensic Jiang, what do you mean by 'seventh strike'?"

"I've determined the sequence of blows from the crime scene. This mark is from the seventh strike," Jiang Yuan replied.

Hou Xiaoyong widened his eyes. "But we just said the first strike didn't bleed, the second did—so shouldn't the third be next?"

"The third strike's bloodstain is probably on the ground, buried under debris. We'll need to lift things to see it," Jiang Yuan answered.

The group understood this answer.

When the old man entered, the shelf was intact, its contents undisturbed. Only as the attacker struck and the victim fled did objects tumble from the unstable shelf.

So the blood from the third strike was covered by falling items—anyone could figure that out.

The difference was: how did Jiang Yuan know the topmost mark was the seventh strike?

Hou Xiaoyong held back for a few seconds, then couldn't bear it: "Let's set the third strike aside—how can you be sure this is the seventh, not the sixth or the tenth?"

Jiang Yuan smiled gently and said softly, "I counted them. I've already reconstructed the entire crime scene in my mind before speaking to you."

Hou Xiaoyong froze.

Too much sleeplessness had dulled his judgment and intelligence.

If he could sleep eight or ten hours, he believed he could reconstruct several steps too.

But this was precisely the misunderstanding that the problem posed to struggling students.

Students who watched teachers or others solve problems step by step often fell into the illusion that they had learned.

In truth, those who merely followed the sequence were still far from true understanding.

Most math problems aren't solved step by step—they start from the end or middle requirement, then work backward to see how to reach it.

Crime scene reconstruction is the same. No bloodstain analysis expert guesses step by step: first here, then there.

That's foolish and burdensome.

For instance, according to Hou Xiaoyong's training, you should look for spatter first—but Jiang Yuan judged the first strike bled not at all. How then?

Similarly, for the second strike: must you examine every single stain, analyze each one, and eliminate possibilities?

Too complicated. Unnecessary.

The correct approach is to first determine whether stains are early, middle, or late—or before or after a key event.

Assign positions to confirmed stains, then fill in the rest. That's the clearer path.

But this is like a crossword puzzle: you need holistic control. To some extent, if you can't fully reconstruct the scene, you can't even reconstruct half of it.

Hou Xiaoyong and the other technicians had never received formal crime scene reconstruction training.

Domestic criminal science technicians learn through various paths; the most common and basic is school curriculum—foundational knowledge, often unused in practice, yet essential for future potential.

For example, bloodstain analysis requires high school physics and chemistry—momentum, angular velocity, concepts that take students months and hundreds of problems to grasp.

A criminal science technician without this knowledge cannot achieve the same level of understanding through last-minute cramming.

Outside school, the two most common paths are self-study and learning from a master within the unit.

Additionally, ongoing training sessions organized by institutions have gradually become the mainstream for technical advancement.

Techniques like extracting DNA from sweat now sound simple and common.

But they were only aggressively promoted around 2008; before that, not only were technicians unable to perform them, but DNA labs often lacked the equipment or reagents.

Crime scene reconstruction is too advanced—among the above paths, only learning from a master makes it possible to develop independently.

That's why TV dramas always portray it as impressive.

Basic bloodstain analysis is sometimes mentioned in training, but Hou Xiaoyong and the others weren't particularly eager learners.

So when Jiang Yuan said he had completed the crime scene reconstruction, the technicians fell into deep thought.

Most of them wondered: How is he going to trick us?

Jiang Yuan waved his hand. "Take another layer from here."

The technicians silently put on gloves and lifted another layer of objects.

"Not yet. Take another layer."

Everyone followed.

The stacked objects pressed on the techs like three girlfriends simultaneously confronting a socialite.

"This should be the mark of the third strike," Jiang Yuan marked it in his notebook.

The others looked over, confused, but trusted Jiang Yuan.

If you can't calculate 857 divided by 648, you just accept someone else's answer.

"This is a later strike location."

"The bleeding patterns are precise."

"From here, the killer entered a state of frenzy."

Jiang Yuan described the crime scene intermittently; unlike performance, his priority now was evidence collection.

As they kept clearing, a tiny blood spot caught Jiang Yuan's attention.

"Wait," Jiang Yuan stopped the technician about to approach.

"What is it?"

"This blood spot—look at its landing point and velocity. It doesn't match the others nearby," Jiang Yuan noticed it at a glance.

But the other technicians stared blankly, lost.

How is it different? They all look the same…

"All blood spots follow a parabolic trajectory. If this one came from the victim, it likely broke off at a sharper angle."

As he spoke, Jiang Yuan had someone take several photos.

"You suspect it came from the killer?" Hou Xiaoyong caught on.

"At minimum, it splashed onto the killer and flew off again. But most likely, it's the killer's own blood."

Jiang Yuan personally carefully collected the blood spot.

Hearing this, the other technicians erupted, gathering again to stare.

"The killer was injured? How?" Hou Xiaoyong asked urgently.

Jiang Yuan glanced at him and whispered, "During the attack, the victim may have resisted. Something may have splashed and struck him, or the weapon may have cut the killer himself…"

Jiang Yuan offered no further explanation. To him, a single drop of blood could decide many things—no need to demand perfection.

Anyone who left blood at a violent crime scene should come to the police station and explain themselves!