Chapter 129: Bloodstain Analysis

As a forensic doctor, even a young forensic doctor, Jiang Yuan gradually began to become immune to the unpleasant smell of the scene.

Standing at the scene, taking a deep breath, it was more of a feeling.

Come to think of it, this was Jiang Yuan's first experience with a bloodstain scene. Although no one died, Jiang Yuan couldn't help but feel refreshed at a glance.

LV5 bloodstain analysis, this was also the first time to use it.

"Jiang Yuan, what did you see?" Wu Jun put on his mask and coughed. He also knew that this was Jiang Yuan's first experience with a bloodstain scene, so he had to determine that Jiang Yuan's state was normal.

In addition, Wu Jun also prepared to see Jiang Yuan's understanding of the bloodstain scene. Anyway, he was a newcomer in the forensic circle, and it was normal to have places he didn't understand.

Jiang Yuan was asked, didn't think much, looked around the scene again to confirm his thoughts, and then pointed to the pool of blood and said: "The bleeding volume of the wounded is very large. A flow-column bloodstain was formed in front of the steps of the house. Therefore, it can be preliminarily considered that this is the position where the wounded lay temporarily after being injured."

Wu Jun nodded. This is a basic judgment. The judgment method for a dead person is the same.

Jiang Yuan also took a photo with his mobile phone and said: "The blood around the pool of blood has dried, and the middle is concentrated blood. Judging from the drying situation of the pool of blood alone, the time of the wounded's bleeding is about 4 hours ago."

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

Jiang Yuan was talking while making simple records in his paper notebook, so as not to forget it later and make a joke—there really were forensic doctors who had similar things happen, which was truly terrifying to have nightmares in the middle of the night, and it was... considered equally terrifying as seeing the parties sit up.

Wu Jun nodded again after listening. The judgment of the time of death has always been the core of forensic skills. All kinds of theories and academic directions will automatically extend in this direction.

Theoretically, forensic doctors will think, how can I use it to judge the time of death of the deceased when picking up a branch at the scene, and the powerful place is that it can really be used to judge the time of death.

Of course, the significance of using the pool of blood to judge the time is actually not very great now, because the wounded is still alive, and the reporter's report is also considered active, so there is basically no doubt about the time of the case.

However, for forensic doctors, every bit of information at the scene is extremely rare, and those that can be judged must be judged.

Then, Jiang Yuan focused his attention on the shape of the bloodstain.

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

In practice, it is actually the same.

Bloodstains have the effect of traveling through time and space, and can be said to be the technology closest to Sherlock Holmes.

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

Like now, Jiang Yuan first walked to the place with splashing bloodstains.

Splashing bloodstains, as the name suggests, are in a state of being sprayed onto an object and then splashing open.

If you are really very curious, you can try not to find the toilet when you have bloody stool, but solve it on the spot. The bloody stool formed by this has the characteristics of splashing bloodstains.

And in bloodstain analysis, splashing bloodstains usually do not come from bloody stool—as everyone knows.

It often comes from the rupture of arterial blood vessels, and is therefore considered to be the starting position of the perpetrator.

Therefore, doing bloodstain analysis, or wanting to reconstruct the scene like a divine detective, traveling through the obstacles of time and space, should start from the splashing bloodstains.

For Jiang Yuan, LV5 bloodstain analysis is exactly the skill to reconstruct the scene. So, he first came to the position of the splashing bloodstains, looked around, and couldn't help... laughing.

Because looking from his position, he happened to see several dripping blood drops, next to the flower bed not far from the splashing bloodstains.

Jiang Yuan walked over immediately.

This position is slightly away from the large pool of blood. And the dripping blood drops are almost perfect circles, without any small tails...

Blood drops with small tails, that is, blood drops like tadpoles, or blood drops with longer tails, like comets, all explain one thing: the blood drops fell on the surface at a certain angle. The longer the tail, the smaller the angle at which the blood drop hits the object surface.

It's like a blood drop dragging a long tail, like a comet, which usually hits the object surface at an angle of less than 30 degrees.

And the blood drop without a tail, that is, the blood drop Jiang Yuan is looking at, falls vertically.

Can you imagine, in a fierce crime scene, under what circumstances will vertically falling bloodstains form?

It is when blood drops fall from a static person or object that such a perfect circular dripping bloodstain will form.

The victim is being hacked, the hand is broken, lying in the pool of blood panting, where is there time to let himself be static, and then let the blood drip vertically.

Besides, the amount is also different.

Therefore, dripping blood drops are most likely to come from the murderer.

Jiang Yuan made a further judgment, because the dripping blood drops are not continuous, but just a few drops, so it doesn't look like bloodstains brought from the victim.

In other words, the dripping blood drops at his feet are likely to come from the murderer himself.

Jiang Yuan also laughed out loud because of this.

Fortunately, he was wearing a mask.

Sometimes, or most cases, maybe you really don't need to reconstruct the scene so complicatedly.

Jiang Yuan squatted down, took photos carefully first, then took a cotton swab to dip the blood, wrapped the cotton swab with filter paper, and folded it into a triangle. This is his consistent practice, and the scene investigation personnel around him have seen it, and they all turned their heads away.

"Young man, your eyesight is really good." Wu Jun walked over and sighed.

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

Passionate crime, facing modern technology, is just so simple and direct.

As for why the murderer would leave bloodstains, this actually involves an experience problem. In fact, many crime scenes will have similar situations. Simply summarized, it is still an experience problem.

A murderer who kills or hacks people for the first time usually has a hard time estimating how much feedback the force will have when this knife is hacked out.

Coupled with the fact that the weapons used are often not handy, and it was an abnormally nervous state at the time, improper application of force and hurting oneself is actually very common. And, because of the role of adrenaline, the injured person will not notice the pain, thereby ignoring the cleaning of the scene.

Why the police always emphasize the first scene when solving cases is because in the first scene, the murderer is prone to flaws.

And why the detection of serial murder cases always likes to find the scene where the murderer killed for the first time is because that is the place where the murderer lacks experience the most, and it is also the place where he is most likely to reveal flaws.

Similarly, why animal abuse is always paid attention to by the police abroad and recorded in the file is because it is often closely linked to violent crime, and it is very likely that a murderer is doing self-cultivation.

"From the blood drops, what can you see?" Wu Jun continued to examine Jiang Yuan, wanting to see if his understanding of bloodstain analysis was qualified.

Jiang Yuan looked down at the other few drops of blood and said slowly: "Judging from the size of the blood drops, the height of the drop is about one meter. It may be that the murderer's arm hung down, and it dripped from the position of the finger."

"En, the judgment is quite accurate. The size of this blood drop is actually not easy to judge. The difference between one meter and 1.2 meters is not very obvious." Wu Jun said his experience.

The higher the place, the larger the blood drops falling down will be, but because an ordinary person's hand hangs down, it is just about one meter, so the blood drops of this size are more concerned.

And the blood drops of 1.2 meters indicate that the injured part is higher, or the murderer's height is different from ordinary people.

With Jiang Yuan's current ability, judging the height of the blood drop falling is easy, and he said easily: "The blood drop falling at one meter is just the size of the cross-section of a straw like Starbucks."

Wu Jun was stunned. How can a forensic doctor who has never drunk Starbucks do things? Fortunately, he knows how big the blood drop falling at one meter is, so he imagined the cross-sectional area of the Starbucks straw in his mind and couldn't help nodding: "That Starbucks straw is quite thick. I thought it was like the AD calcium milk before."

Jiang Yuan understood and said: "I will ask someone to bring Starbucks from Changyang City later. Let's drink coffee while doing the case."

Wu Jun nodded in agreement and added: "Okay, then we will drink coffee, smoke Zhonghua, and educate this murderer well."

Just talking, a criminal police officer brought someone to the gate of the courtyard and shouted inside: "The victim's family is here."

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

The eyes of the two lit up.

Wu Jun first gave a wink to the two criminal police officers standing next to him. After the two criminal police officers walked out of the courtyard gate and walked a few steps forward, arriving behind the man, Wu Jun asked the man casually: "How did you get injured?"

The man said with a hoarse voice: "I fought with the gangster and was injured."

"This is the victim's husband, who just bandaged in the relative's house next door." The criminal police who brought him over saw this posture, and also understood, while talking, grabbed the man's injured arm, as if showing it to everyone, and said: "The injury is not too heavy, just bled a little."

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

"Just... just there..." The man pointed to a position, which was near the flower bed.

"Then how did you get injured?"

"The other party picked up a firewood knife to hack, and I blocked it."

"Where did you block it?"

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

Wu Jun and Jiang Yuan both showed smiles. There was no splash injury, how dare you say you blocked the knife? ===== CHAPTER 130 =====