Chapter 288: Small Details

Reconstructing the scene can be understood as: I am going to simulate the crime once.

Simply put, it's where I enter the scene, whether from the front door or the roof, from the window or the floor, or learn from medieval assassins and launch a surprise attack from the bottom of the dry toilet.

The way of entering the scene can be assumed, the actions within the scene can be simulated, and the way and position of leaving the scene are the same.

If there is sufficient blood to perform bloodstain analysis, Jiang Yuan can reconstruct the scene very beautifully, because blood can simultaneously display the position, speed, and acceleration of the murderer and the victim.

Honestly, this skill of bloodstain analysis is sometimes more useful than installing several detectors on the murderer, and even more concrete and real than what is shot by surveillance cameras.

Of course, this is the best state.

Ordinary criminal investigation personnel can only complete the two ends, which is not bad. The middle part of the crime, especially the specific actions and steps of the murder, basically does not involve too much. That part can be completed by the forensic doctor. En, it is still Jiang Yuan in the end.

And as far as the scene today is concerned, there is not much blood, so the clues given are actually few.

But for Jiang Yuan, the limited blood also explains many problems. For example, the murderer's movement, he probably entered from the door, and after two or three steps, he began to accelerate, directly hitting the cashier with a stick, and then struck again.

Just from these two decisive actions, the murderer is very decisive. He probably knew there was money here, and it was even premeditated. Jiang Yuan followed the direction of the blood splashing and looked. The murderer should have carried the murder weapon, collected the money, and continued forward...

Ahead, it is the position of the window.

Jiang Yuan stood still, tilted his head and asked He Guohua: "How do you judge the murderer's movement, from where, to where?" He Guohua was originally waiting a bit lonely. Hearing the question was so basic, he just thought Jiang Yuan was asking casually, so he said: "Enter from the front door here, beat the cashier to death, take the money, and then run out?"

His tone is uncertain. Originally, it was like this. There are not many traces in the room indicating the murderer's movement.

Regardless of the ability to investigate the crime scene or the ability to analyze bloodstains, everyone has obvious gaps.

Jiang Yuan didn't sell it either, and said directly: "The murderer jumped down from the window."

"Ah" He Guohua was stunned for a moment, walked forward two steps, suddenly stopped, turned around and went to the door to carry several transparent small acrylic stools, paved a few towards the window, and then stood at the window to look down.

"Is this footprint the murderer's landing footprint?" He Guohua was a little pleasantly surprised.

The problem now is not that there are no footprints, but that there are too many footprints, and there is no way to identify them. If it can be determined which footprint is the murderer's, it is a big breakthrough.

Wang Bo, who was a high-latitude creature before, was not covered up by his master's surprise, and asked with the spirit of independent thinking: "Master, first to determine, shouldn't it be this murderer's movement? Why did the murderer jump down from the window?"

"Grandpa Jiang said it was jumping down from the window." He Guohua glared at his apprentice and leaned out to look: "Look at the footprint below, does it look like a footprint of jumping down? Would a normal person jump down from the second floor?" The first-floor window might also jump out of people...

The first-floor window is welded with steel bars. Let you pay attention to observation at ordinary times. What did your eyes see?

"He Guohua turned around and scolded his apprentice.

Xiaobo originally wanted to question Jiang Yuan, but his business strength hadn't been trained yet, and he was struck by dimensionality reduction here by He Guohua. Wang Bo wanted to struggle, and added: "Then Wu Wu Fa Yi Jiang didn't look downstairs just now..."

"Doesn't that make Grandpa Jiang even more awesome?" He Guohua completely entered the online state, looking at Wang Bo as if looking at an enemy keyboard player.

Wang Bo shrank his neck and just muttered: "There is a good road not to walk, no one found it, why doesn't he walk the door?"

This question is where the difficulty lies. He Guohua looked directly at Jiang Yuan. Jiang Yuan spread his hands and said: "I can't say for the time being, but judging from the traces at the scene, the murderer just did this."

Actually, to guess, the reason

can be many. For example, the murderer is a parkour player, there is a good road not to walk, just walk this kind of place; or the murderer is excited, just jumped down directly; or the murderer just wants to use this way to confuse the investigation; or there may be more than one murderer, and someone temporarily decided to eat black and black...

Jiang Yuan has no evidence to reason about this for the time being, and he doesn't want to guess for this for the time being.

His goal is to solve the case, not to convince young people like Wang Bo. If the latter is too troublesome, he will just replace him. He Guohua was much more obedient, immediately following Jiang Yuan's train of thought, and said: "In this way, the murderer can first be assumed to be a young man. Relax a bit, people in their thirties, forties, generally speaking, should not choose the road of jumping out of the window."

"The age is about thirty." Jiang Yuan also walked to the window, looked at the footprints on the ground from top to bottom, made a judgment, and said: "First collect the footprints below, and then come up to find the corresponding ones."

The footprints downstairs were caused by jumping down, and the imprints were quite clear. Correspondingly, although the ground upstairs cannot see the footprints, as long as they are collected, there will still be imprints left, but it may require the cooperation of some instruments.

Thinking of Jiang Yuan's footprint identification ability, He Guohua's fire of hope was already burning fiercely, and he picked up the investigation box and left.

The sooner footprints are collected, the better, especially this kind of outdoor footprints. It is hard to say that a wind or a rain will wipe them out.

The current homicide cases are relatively easy to solve, actually there is also a reason, that is, murderers like to commit crimes indoors. From the statistical data, the place where most crimes are committed is still at their own home.

This creates a situation where the traces of crime are particularly difficult to eliminate. Like blood, blood remaining indoors may remain for ten years. Where is it like the wild, it doesn't take a few months, a few weeks, it basically disappears.

Of course, there are too many surveillance cameras outside, which is the main reason why everyone makes this choice.

Changyang City has an electrostatic adsorption instrument professionally used for footprint extraction. It is actually a palm-sized instrument with several knobs on it, slightly adjusted. He Guohua arrived downstairs, first took a few photos of the footprints, then took out the electrostatic adsorption instrument, put it aside, and took out an insulating paper, covering it on the footprints.

The insulating paper is black, a bit similar to old-fashioned carbon paper.

It is full of static electricity itself, looking a bit irregular.

After placing the insulating paper, He Guohua stuck the two corners of the electrostatic adsorption instrument on the insulating paper, grounded one foot, turned on the switch of the electrostatic adsorption instrument, and the insulating paper immediately stuck to the ground.

"Roller." He Guohua reached out, and the apprentice next to him immediately handed it to him.

He Guohua held the roller, pushed it gently on the insulating paper a few times, and explained to the apprentice: "Just push it flat, don't use too much force, and use adhesive later."

"Oh."

Wang Bo nodded.

He Guohua handed the roller back to the apprentice, then gently peeled off the insulating paper, took a look at the angle of the light, and saw that the footprints had been clearly copied onto the insulating paper.

He Guohua put the insulating paper into the box and processed it after returning to the laboratory.

Subsequently, He Guohua took out the adhesive.

The adhesive is a black adhesive paper, the size of a standard A4 paper, and it looks like a mouse-sticking paper, and the surface is also pitch black.

The adhesive is even simpler to use. It is directly covered on the footprints, also brushed with a roller, or even pressed twice by hand, and then pulled up directly.

However, after the adhesive treatment, the footprints on the ground are considered damaged, which is why electrostatic is done first, and then adhesive is done.

Returning to the crime scene upstairs, He Guohua opened the investigation lamp, adjusted the light source, and scanned the footprints on the ground.

Even if the footprints on the ground cannot be seen with the naked eye, if you hit them with an investigation lamp, they will be clearly visible.

Investigation lamps are all variable wavelength, and you can use wavelength adjustment if you really can't see them, but generally speaking, white light is enough.

He Guohua continued to collect the footprints.

Looking up again, Jiang Yuan was staring at the window.

"Brother Jiang

, finished scanning." He Guohua reported.

"En... have you scanned the window frame? Did you get fingerprints?" Jiang Yuan gestured with his hand.

The window frame is made of plastic, and taking fingerprints itself is difficult. He Guohua smiled and said: "There are fingerprints taken, I don't know if there are any of the murderer."

"Then let's take it again." Jiang Yuan asked for the investigation box and started brushing.

He Guohua hesitated: "Do you think the murderer touched this window frame?"

"You can try to simulate it. Can you do it without touching the window frame while holding the murder weapon in one hand and jumping out of the window?" Jiang Yuan gestured. He Guohua also gestured, and couldn't help but mutter to himself: "Really..."

Wang Bo said softly: "I can be two meters away from the window, jump hard, both feet off the ground, pass through the window, and then land with both legs..." Wang Bo not only narrated, but his body also moved, his feet swaying on the board bridge, just not crooked.

He Guohua helplessly said to Jiang Yuan: "He is a minor in gymnastics. National first-class athlete."

Jiang Yuan could only spray twice and said: "Is it so rolled? If it is national first-class, let him go and get some printer toner."

"Um... good. Is it used to brush fingerprints?" He Guohua asked, and without waiting for an answer, he sent Wang Bo out.

In the blink of an eye, Wang Bo was already running in the sun.

Jiang Yuan nodded and said: "This kind of plastic material is very likely to have no fingerprints. You can use printer toner mixed with magnetic powder to brush."

Jiang Yuan talked about small techniques, He Guohua quickly wrote them down. On-site investigation is a delicate job, and what really tests is actually these small places. ===== CHAPTER 289 =====