Chapter 135: High-End

Late at night.

Even the owls were asleep.

After hearing Jiang Yuan's words, the group of technicians regained some of their drive.

In the small courtyard of the elderly scavenger, right by the entrance, several technicians gathered together, standing behind Jiang Yuan, listening to him speak while observing the bloodstains on the ground.

Under the glare of the floodlights, the color of the blood looked slightly distorted, but one could still vaguely feel the cruelty within it.

The spot Jiang Yuan pointed to with his finger was one of the few areas in the courtyard not covered by objects; several blood spots were quite conspicuous.

"It doesn't look like there are any spatter-type bloodstains here either." Hou Xiaoyong had also studied bloodstain pattern analysis, but his skills were mediocre, and he only knew some common knowledge.

Jiang Yuan just nodded slightly and said, "Books say that spatter-type bloodstains often indicate the primary scene and the starting point of the assault. But at today's scene, the lethality of the weapon used by the perpetrator was clearly insufficient. This suggests from another angle that the perpetrator's initial goal might not have been murder."

Jiang Yuan gestured near his own head and added, "From the surrounding cast-off bloodstains, you can actually tell that the perpetrator likely used a blunt object. Also, look at the velocity of the cast-off stains. It's more obvious on the wall over here."

The group then gathered around to look at the bloodstains on the wall.

On the wall built of red bricks and cement, the stains were mostly oval and elongated, with some tiny blood droplets in front.

"These are characteristics of relatively high-velocity bloodstains, indicating that the blunt object wasn't very heavy and might have been quite long." Jiang Yuan analyzed as he looked.

Several technicians nodded along, indicating they knew this common knowledge.

"So, the first strike might not have caused bleeding. It also didn't produce spatter-type bloodstains." Jiang Yuan glanced at Hou Xiaoyong, which served as an answer to his question.

Hou Xiaoyong couldn't help but nod slowly as he listened.

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

"But after being struck, Zhang Hong—the deceased scavenger—made an evasive movement. The blood on the handprints here was pressed on later; you can see he was lunging forward." Jiang Yuan pointed further ahead and said, "The appearance of cast-off bloodstains here indicates that the second strike broke the scalp."

Jiang Yuan walked two more steps forward, and in front of him lay a pile of collapsed objects.

"These are the traces left during the seventh strike. Take photos, collect the bloodstain evidence first, and the rest can be set aside to be collected slowly later." Jiang Yuan waved his hand in front of him, effectively marking off a section.

Hou Xiaoyong and the others, who were following Jiang Yuan to learn how to reconstruct a crime scene, were stunned and felt a bit at a loss.

"You ask."

"You ask."

Several technicians exchanged glances.

The senior technician, tired of the back-and-forth, flared up with his eyes, glaring at everyone to signal: "Are you asking or not? If you don't ask, I'm not going to bother. What are you pretending for at a time like this? When you get asked about it later, who among you is going to answer?"

Hou Xiaoyong sighed and asked aloud, "Forensic Doctor Jiang, what do you mean by the seventh strike?"

"It means that based on my judgment of the strike sequence at the crime scene, this is what was left during the seventh strike." Jiang Yuan replied.

Hou Xiaoyong widened his eyes and said, "Didn't we just say the first strike didn't bleed, the second one bled, and then it should be the third strike?"

"I estimate the bloodstains from the third strike are on the ground; we'll have to lift these up to see them now." Jiang Yuan answered.

The group could actually understand this answer.

When the old man entered the door, the shelving unit was still fine, and the items were all placed properly on it. It was only as the perpetrator attacked and the victim tried to evade that a large number of items fell from the unstable, makeshift shelving unit.

So, the bloodstains from the third strike were buried by the items on top; anyone could figure that out.

The difference was, how did Jiang Yuan determine that the ones on top were from the seventh strike?

Hou Xiaoyong endured for a few seconds, but still couldn't hold back and asked, "Let's not even talk about the third strike's bloodstains; on what basis do you say the ones on top are the seventh, and not the sixth, or the tenth?"

Jiang Yuan smiled warmly and said softly, "I counted them out. I had already completed the crime scene reconstruction in my mind before I told you all."

Hou Xiaoyong was instantly stunned.

It was also because he had been staying up too late, causing his judgment and IQ to start dropping.

If he could sleep for eight or ten hours, he felt he could definitely reconstruct a few steps too.

However, this was actually the misunderstanding that all difficult problems give to poor students.

Students who look at the steps of a teacher or someone else solving a problem, following the sequence step by step, often fall into the misconception that they have learned it.

In reality, students who follow the sequence mechanically are still very far from truly learning it.

Most math problems are not solved step by step; rather, one looks at the requirements at the end or in the middle first, and then looks at how to reach those requirements from the beginning.

It's the same with crime scene reconstruction; no expert in bloodstain pattern analysis actually guesses where the first step is, then where the second step is, guessing step by step like that.

Doing so is too foolish and creates too many unnecessary burdens for oneself.

Just like the first step, according to the information Hou Xiaoyong learned, it seems one should look for spatter-type bloodstains, but according to Jiang Yuan's judgment, the first strike didn't cause bleeding—so what do you do then?

And as for Jiang Yuan's second step, it was similar. If you wanted to find the second strike, would you look at every single bloodstain and analyze them one by one? Then you would still have to rule out the possibility that other bloodstains were the second strike.

Too troublesome and unnecessary.

The correct approach is to first determine whether the bloodstains are from the early, middle, or late stages, or whether they occurred before or after a landmark event.

Arranging the confirmed bloodstains in their positions and then slowly filling in the blanks with the remaining stains is the relatively simpler problem-solving step.

However, this is like a crossword puzzle; it requires overall control. To some extent, those who cannot fully reconstruct the crime scene cannot even reconstruct half of one.

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

There are many ways for current criminal science and technology personnel in the country to learn things. The most common but most basic way is through school courses. These things are the foundation of foundations and might not even be used in practice, but if one doesn't learn them, subsequent development potential is very low.

For example, in bloodstain analysis, it uses some high school physics and chemistry knowledge, such as momentum, angular velocity, and the like. High school students actually need several months and hundreds of problems to understand these.

If a criminal science and technology professional hasn't mastered the corresponding knowledge and tries to cram at the last minute, it's unlikely their level of understanding will be the same.

Besides the learning paths outside of school, reading books and apprenticing at one's unit are the two most common modes.

In addition, various training activities organized by units have gradually become the mainstream for technicians to improve.

Technologies like sweat DNA extraction sound simple and common now.

But this was also pushed vigorously around 2008. Before that, not only could technicians not do it, but the equipment and reagents in DNA laboratories couldn't necessarily support it either.

Something like crime scene reconstruction is too high-end. Apart from finding a master to teach you, it's basically very difficult to practice it on your own.

That's why TV shows always feature it—because they think it's awesome.

Basic forms of bloodstain analysis and the like are mentioned during training, but Hou Xiaoyong and the others weren't exactly the type to be particularly studious.

In short, when Jiang Yuan said he had already completed the crime scene reconstruction, several technicians fell into deep thought.

Most of them were thinking: How is he planning to fool us?

Jiang Yuan waved his hand and said, "Collect another layer here at the back."

Several technicians, without a word, put on their gloves and collected another layer of objects.

"Still not there, then collect another layer."

Everyone followed suit and collected.

The pressure brought upon the tech-geeks by the stacked objects was no less than having three girlfriends show up at once to confront a "normie."

"This should be the traces left during the third strike." Jiang Yuan made a mark in his notebook.

Several people looked over, not understanding, but could only trust Jiang Yuan.

If you can't calculate 857 divided by 648 in your head, then when you hear the result from someone else, you can only listen for the time being.

"This is the location of the later strikes."

"The bleeding locations are very particular."

"From here on, the perpetrator entered a state of excitement."

Jiang Yuan described the crime scene intermittently. Unlike performing, his most important work now was collecting evidence.

As they dug and dug, a tiny blood spot caught Jiang Yuan's attention.

"Wait." Jiang Yuan stopped the technician who was about to step forward.

"What's wrong?"

"Look at the landing point and velocity of this blood spot; it doesn't belong to the same group as the other blood spots nearby." Jiang Yuan noticed this blood spot as soon as he glanced at it.

But at this moment, the other technicians were all staring blankly with dazed eyes.

Where is the difference? It clearly looks the same...

"All blood spots, their trajectories in the air, are basically parabolas. If this blood spot came from the deceased, it would likely cut a smaller angle."

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

"You suspect this was brought by the perpetrator?" Hou Xiaoyong caught the implication.

"At the very least, it's blood that splashed onto the perpetrator and then flew off. But the greatest possibility is that it's the perpetrator's own."

As Jiang Yuan spoke, he did it himself, carefully collecting the blood spot in front of him.

Hearing him say this, the other technicians were stirred up and gathered around again to stare.

"The perpetrator was injured? How were they injured?" Hou Xiaoyong asked anxiously.

Jiang Yuan glanced at him and said in a low voice, "During the crime, the deceased might have resisted; perhaps something splashed up and hit them somewhere, or perhaps the weapon injured the perpetrator themselves..."

Jiang Yuan had no intention of explaining further. To him, a single drop of blood was enough to decide many things, and there was no need to be overly demanding.

Someone left bloodstains at the scene of a violent crime, so no matter who they are, they should come to the police station to explain the situation! ===== CHAPTER 136 =====