As a forensic expert, even a young one, Jiang Yuan had gradually become immune to the unpleasant smell at the crime scene.

Standing at the scene, he took a deep breath, filled with a sense of reflection.

This was Jiang Yuan's first time dealing with a bloodstain scene. Although no one was dead, at first glance, Jiang Yuan felt a surge of adrenaline.

This was also his first time using level 5 bloodstain analysis.

"Jiang Yuan, what have you found?" Wu Jun asked, putting on his mask and clearing his throat. He knew this was Jiang Yuan's first time at a bloodstain scene, so he needed to make sure Jiang Yuan was in a normal state.

Moreover, Wu Jun was also prepared to see how much Jiang Yuan understood about bloodstain scenes. After all, he was a newcomer in the field of forensics, and it was normal to have areas of uncertainty.

When asked, Jiang Yuan didn't think too much. He looked around the scene again to confirm his thoughts, then pointed at the pool of blood and said, "The victim lost a lot of blood. There are columnar bloodstains in front of the steps of the house, so I preliminarily believe this is where the victim lay after being injured."

Wu Jun nodded. This was a basic judgment, the same method would be used even if the victim was dead.

Jiang Yuan took a photo with his phone and said, "The blood around the pool has dried, and the blood in the middle is concentrated. Judging from the drying condition of the blood pool, the victim's bleeding time was about 4 hours ago."

If this were a murder case, the time of death could also be calculated in the same way.

As Jiang Yuan spoke, he made simple notes in his paper notebook to avoid forgetting later - there had been forensics who had forgotten, which was a nightmare, even more terrifying than seeing the victim sit up.

Wu Jun nodded again. The determination of the time of death has always been the core of forensic skills. Various theories and academic directions will automatically extend in this direction.

In theory, a forensic expert could pick up a twig at the scene and think about how to use it to determine the time of death. The amazing thing is, it really can be used to determine the time of death.

Of course, the significance of using the current blood pool to determine the time is not very big, because the victim is still alive, and the person who reported the case was quite proactive, so there is basically no doubt about the time of the incident.

However, for a forensic expert, every piece of information at the scene is extremely valuable. If a judgment can be made, it must be made.

Next, Jiang Yuan focused on the shape of the bloodstains.

In bloodstain analysis, the shape of the bloodstain is more important than its content.

In practice, this is also the case.

Bloodstains have the effect of transcending time and space, and can be said to be the closest technique to Sherlock Holmes.

At a violent crime scene, when a large amount of blood appears, it often means that the technicians can reconstruct the crime scene based on this. This reconstruction is not nominal, but can really reconstruct every step of the perpetrator's actions against the victim, and even every step of the victim's actions before bleeding.

For example, at this moment, Jiang Yuan first went to the place with splattered bloodstains.

Splattered bloodstains, as the name suggests, are the state of being sprayed onto an object and then splashing out.

If you are really curious, you can try not to find a toilet when you have bloody stools, and solve it on the spot. The resulting bloody stools will have the characteristics of splattering.

In bloodstain analysis, splattered bloodstains are usually not from bloody stools - as is well known.

They often come from ruptured arteries and are therefore considered to be the starting point of the attack.

Therefore, to do bloodstain analysis, or to be like a detective, to break through the barrier of time and space and reconstruct the scene, you should start with splattered bloodstains.

For Jiang Yuan, level 5 bloodstain analysis is a good skill for reconstructing the scene. So, he first came to the location of the splattered bloodstains, looked around, and couldn't help but... laugh.

Because from his position, he could see several droplet-shaped blood drops, right next to the flower bed not far from the splattered bloodstains.

Jiang Yuan immediately walked over.

This location was slightly away from the large pool of blood. And the droplet-shaped blood drops were almost perfectly round, without a little tail...

Blood drops with little tails, like tadpole-shaped blood drops, or blood drops with longer tails, like comet-shaped blood drops, all indicate one thing, that the blood drops fell on the surface at a certain angle. The longer the tail of the blood drop, the smaller the angle at which it hits the surface.

Just like a blood drop with a long tail, like a comet, it usually hits the surface at an angle less than 30 degrees.

And the blood drops without tails, the ones Jiang Yuan was looking at, fell vertically.

You can imagine, in a violent crime scene, under what circumstances would there be vertically falling bloodstains?

It is when blood drops fall from a static person or object that such perfectly round droplet-shaped blood drops are formed.

The victim is being chopped, his hand is broken, he is lying in the blood pool gasping for breath, where does he have the time to calm down and let the blood drop vertically.

Moreover, the amount is also different.

Therefore, droplet-shaped blood drops are most likely to come from the perpetrator.

Jiang Yuan further judged that because the droplet-shaped blood drops were not continuous, but just a few drops, they did not look like bloodstains brought over from the victim.

In other words, the droplet-shaped blood drops under his feet were likely to come from the perpetrator himself.

That's why Jiang Yuan laughed.

Luckily he was wearing a mask.

Sometimes, or rather, in most cases, it may not be necessary to reconstruct the scene in such a complicated way.

Jiang Yuan squatted down, first took a careful photo, then took a cotton swab to dip in the blood, wrapped the cotton swab with filter paper, folded it into a triangle, this was his usual practice, the scene investigators around him had seen it, and now they all turned their heads away."Young man, good eyesight indeed." Wu Jun walked over, making a comment.

He could also tell that this was likely the blood left by the murderer. In other words, with these few drops of blood, the case was basically solved.

Crimes of passion, in the face of modern technology, are just that simple and direct.

As for why the murderer would leave blood behind, this actually involves a matter of experience. In fact, many crime scenes will have similar situations. To put it simply, it's a matter of experience.

First-time murderers or attackers often find it hard to gauge how much force will rebound when they strike.

Moreover, the weapon they use is often not suitable, and they are in an extremely nervous state at the time. Improper exertion of force, injuring themselves, is actually quite common. And because of the effect of adrenaline, the injured person may not even feel the pain, thus neglecting to clean up the scene.

The reason why police always emphasize the importance of the first crime scene is because it is at the first crime scene that the murderer is most likely to leave traces.

And the reason why the police always like to look for the first crime scene of a serial killer is because that is where the murderer is most inexperienced and most likely to make mistakes.

Similarly, why is animal abuse always monitored and recorded by the police abroad? Because it is often closely linked to violent crimes, and it could very well be a murderer practicing his craft.

"What can you tell from the blood drops?" Wu Jun continued to test Jiang Yuan, wanting to see if his understanding of bloodstain analysis was up to par.

Jiang Yuan looked down at the other drops of blood and said slowly, "Judging from the size of the blood drops, the height of the drop is about one meter. It's probably from the murderer's arm hanging down, and the blood dripped from the fingertips."

"Hmm, your judgment is quite accurate. The size of this blood drop is actually not easy to determine. The difference between a drop from one meter and one meter twenty is not very obvious." Wu Jun shared his own experience.

The higher the drop, the larger the blood drop will be. But because the average person's hand hangs down at about one meter, this size of blood drop is of particular interest.

A drop from one meter twenty indicates that the injury is higher, or that the murderer's height is unusual.

With Jiang Yuan's current ability, determining the height of the blood drop was a piece of cake. He casually said, "The size of a blood drop from one meter is about the cross-sectional size of a Starbucks straw."

Wu Jun was taken aback. How was a forensic who had never had Starbucks supposed to work with that? Fortunately, he knew how big a blood drop from one meter was, so he imagined the cross-sectional area of a Starbucks straw in his mind and nodded, "So Starbucks straws are quite thick. I thought they were all like the straws from Ad calcium milk."

Jiang Yuan understood and said, "Let's have someone bring Starbucks from Changyang City next time. We can drink coffee while working on the case."

Wu Jun nodded in agreement and added, "That sounds good. We can drink coffee, smoke Zhonghua cigarettes, and give the murderer a good lesson."

Just as they were talking, a detective brought someone to the gate of the courtyard and shouted, "The victim's family is here."

Jiang Yuan and Wu Jun looked over and saw a man in his forties following the detective, his right hand wrapped in gauze.

Both of them couldn't help but perk up.

Wu Jun first gave a signal to the two detectives standing nearby. After the two detectives left the courtyard and walked a few steps forward to the man's back, Wu Jun casually asked the man, "How did you get hurt?"

The man rasped, "I fought with the culprit and got hurt."

"This is the victim's husband. He just got bandaged up at a relative's house next door." The detective who brought him over understood the situation and, while speaking, grabbed the man's injured arm as if to show everyone. He added, "The injury is not too serious, just a little blood."

Wu Jun nodded and asked again, "Where did you fight?"

"Just... just there..." The man pointed to a location near the flower bed.

"How did you get hurt?"

"The other party picked up a machete to chop, and I blocked it."

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"Where did you block it?"

"Just there." The man pointed to the flower bed again.

Both Wu Jun and Jiang Yuan couldn't help but smile. There were no signs of a splatter injury, and he had the audacity to claim he had blocked a knife?