In accordance with the principle of not destroying evidence, he brought the computer into the conference room, cleared a large area of the table, and Wang Liang quickly disassembled the display screen.
A dozen years ago, assembling a computer was a technical job, and you could get paid for assembling it once. Now, almost everyone who plays with computers can do it. But this does not mean that everyone can disassemble the display screen and examine it.
Most people have never taken a display apart.
Wang Liang spent more than half an hour carefully disassembling the display screen, removing all the wires that could be removed.
"This display screen has only been disassembled once. It was done by Wang Huadong a few days ago. There are only signs of disassembly once." Wang Liang finally said.
"You can see this?" Wang Huadong came closer, obviously not trusting Wang Liang's level of traceology.
"Basically anyone who sells mobile phones can tell if a phone has signs of disassembly. Many of your screws have only been used once, and the same screwdriver was used. Who else could it be but you?" Wang Liang finally confirmed, "Can this be reassembled? There's no point in investigating."
"Okay." Bai Song nodded and said expressionlessly, "Next, check the main chassis."
Bai Song had already seen that Wang Liang's disassembly was much more thorough than Wang Huadong's. Wang Huadong simply opened it, removed the large parts, and then carefully looked to see if there were any special structures. That was it.
At this time, the large round table in the conference room was already full of people.
Everyone came. Those staying in the hotel were on business trips just for this case. When they heard about this, they had to come and see what was going on.
"The computer case has been disassembled many times." Wang Liang said, "Memory sticks have also been added, but this is normal. This is originally an assembled computer. I guess they bought new memory after playing with it for a few years because the memory was not enough."
"This is normal. Be careful with the dust and take your time dismantling it." Bai Song said.
"Inspector Bai, what can we find?" Captain Wang asked, "What could be the problem here?"
"I'm not sure either." Bai Song frowned and watched Wang Liang dismantle the computer.
"Take out the CPU and let me take a look." Bai Song said.
"Why are you taking this apart? Aren't you taking apart the memory?" Wang Liang asked curiously.
"Tear it down." Bai Song didn't say much.
"Okay." Wang Liang found that it was a very happy thing to have someone give him orders.
When he had no clues in handling a case, he would collapse. But when he could come up with clues and arrange useful work, Wang Liang felt more motivated to work. Over the years, Wang Liang had become accustomed to listening to Bai Song when handling a case.
There is a fan outside the CPU, and a very simple heat sink underneath. Only after removing it can you see the CPU. The heat sink of a good computer is copper core, and this one is probably aluminum.
There was dirt all over the place, and Wang Huadong didn't clean it up at all. It wasn't that Wang Huadong was lazy, but the previous disassembly was done in the room where the computers were placed, so there was no need to clean up the dirt.
The CPU is dirty and greasy, which looks disgusting. I guess it hasn't been cleaned for at least four or five years.
"Is this normal?" Bai Song asked.
"It's normal. Everything is normal in this broken computer. It's normal for a few hairs to get caught in the fan." Wang Liang said, feeling a little disgusted. "I installed it."
"Unplug the CPU," Bai Song continued.
"This thing fits tightly. If there's even a little bit of it, the computer won't start up," Wang Liang continued, fearing that Bai Song wouldn't believe him.
Seeing that Bai Song was unmoved, Wang Liang could only gently take out the CPU. Just for this simple action, more than a dozen people craned their necks to watch.
"Look, there's nothing." Wang Liang raised the CPU.
Nothing is normal. If something useless can be stuffed between the CPU, which is such a sophisticated device, and the motherboard and still allow the computer to run normally, then if you have the technology, you might as well just assemble a lithography machine by hand.
"What is that? Bai Song pointed to a white line under the CPU slot." This white line is very, very thin. If it weren't for the darkness around it, it would not be visible at all.
As soon as Bai Song said this, everyone stood up and gathered around.
Wang Huadong immediately took out a magnifying glass and moved closer, and Wang Liang quickly moved away.
You can see from the magnifying glass that there is a little bit of white powder seeping into the edge of the CPU. If you don’t look carefully, you really can’t see it clearly.
There is too much dirt and dust in here. The CPU fan keeps spinning when the computer is powered on, and there is hot air here, which basically blows away everything. However, some dust is still left in this gap.
"Huadong, do you still remember the aluminum alloy doors and windows in the Yao Xin case?" Bai Song asked.
Wang Huadong was struck by lightning!
yes!
Many traces of the scene will be destroyed.
In the Yao Xin case, the fire and firefighting destroyed 99% of the evidence at the scene. Only a little foam residue was found in two tightly fitted aluminum alloy doors and windows, which became the key evidence in solving the case.
Everyone originally thought that this case was very calm and there was no possibility of evidence being lost. However, no one had ever thought that an open computer was actually the best means of continuously destroying evidence.
The victim was found several hours after his death, and the computer was still running.
On a microscopic level, the high temperature of the CPU and fan is no less harmful than a fire or a flood.
"What is this white powder?" someone asked.
"Could it be cyanide?"
"Then open the window quickly and don't get so close."
"Fuck, this is scary," someone immediately went to open the window.
"Don't move!" Bai Song stopped the policeman who was about to open the window: "Cyanide will decompose quickly in the air, how can it be stored for so long?"
Bai Song's words seemed to have a magical power. Everyone immediately stopped being anxious. Someone asked directly, "Inspector Bai, what is this?"
"This requires final testing." Bai Song saw that everyone's expressions were a little disappointed: "But, this thing has a high probability of being sodium formate."
"What?"
“What is sodium formate?”
"It's baking soda, soda ash."
"That's sodium formate..."
"Oh, how come there is this..."
Bai Song ignored the others and asked Wang Liang, "Based on your experience, what temperature can the CPU reach when running those legendary games on this broken computer?"
"Normally, the temperature of a CPU won't exceed 55 degrees Celsius when it's running a game, but this computer's heat dissipation isn't good. Neither the CPU nor the motherboard is good. It's estimated to be over 70 degrees." Wang Liang estimated.
"Yeah." Bai Song looked at everyone: "Of course, this could also be potassium formate, etc. In fact, this matter is not that troublesome. What I want to say is that the murderer killed people by relying on this CPU."
"Inspector Bai, you mean that the murderer put the cyanide here?" Captain Zhao asked, "If that's the case, when was it put in? If it was put in fifteen days before the crime, how could cyanide be preserved for so long?"
"Originally it wouldn't work, but sodium cyanide sealed with wax can." Bai Song said shockingly: "Many substances that can react with air are stored in paraffin or kerosene. Many things in our daily lives can also be sealed with melted household candles. If you take a small amount of sodium cyanide, seal it with wax, and put it between the CPU and the fan, there will be no problem on weekdays. But when Xiao came back and turned on the computer to play games, the CPU got hot, and there was a big problem! You know, household candles will soften above 40 degrees, and will simply melt at 70 or 80 degrees. Under this fan, the melted paraffin would have been blown away and merged with the dust into a greasy state. Sodium cyanide will naturally hydrolyze to form hydrogen cyanide in humid air, and it can decompose rapidly above 60 degrees."
"It's actually possible!" Wang Liang was a little excited: "So, the murderer entered this room fifteen days in advance, and then placed the wax-sealed sodium cyanide here, and then waited for Xiao to press the death button himself!"
Thinking of this, Wang Liang looked at the power button with some trembling, and murmured: "I didn't expect that this is actually the death button..."
Wang Huadong was speechless when he saw Wang Liang's immature look. He looked at Bai Song and asked, "Why is there sodium formate left?"
"Sodium cyanide meets water and carbon dioxide in humid air and can produce substances such as sodium formate and hydrogen cyanide. Hydrogen cyanide is highly toxic, and a few milligrams per cubic meter are dangerous to the human body. In a humid environment above 60 degrees, the concentration of hydrogen cyanide will quickly reach a lethal dose. Sodium formate will not continue to decompose at this temperature, so these things should be the remaining potassium formate. The others were blown everywhere by the fan and mixed in the dust." Bai Song explained: "This is the method of killing."
"Inspector Bai, you look confident, if you have anything else to say, just say it all." A superior expert looked at Bai Song and said with some interest.
"Hello, Mr. Sun," Bai Song greeted him first, and then said, "At the moment, I think the murderer may be one of the people whose electric vehicle batteries were stolen."
When Bai Song said this conjecture, no one was surprised, but a few people were a little confused. Because at the beginning, many people thought about this question, but there was no other evidence to support it.
"Let me continue," Bai Song cleared his throat, "The reason why we didn't find this when we checked the families whose batteries were stolen is probably because this family didn't call the police. Over the years, except for some people who don't care about electric vehicle batteries, the others didn't call the police, probably because they don't trust the police. Why do I say that this person did it? Because there are several good conditions for committing the crime.
First, Xiao lost one of his keys. As a new thief, he probably dropped it while stealing and it was picked up by the owner. Second, the police had visited several communities and asked if any electric bike batteries had been stolen. The suspect had been arrested. So the person who lost the electric bike also knew who stole it. There wasn’t a big place nearby, so just asking anyone would probably know that it was Xiao who was detained. Third, the police went to Xiao’s home to check. If the murderer wanted to know where Xiao’s home was, he could find out by following the police. The police station would not care about anything else when handling a theft case, and would not pay attention to being followed secretly.
"This doesn't make sense. Why don't you trust the police? Since the person who lost the bike already knows that the police have caught the thief, why don't they call the police?" someone asked.
"This is almost inevitable. Someone who can commit murder, and such a sophisticated act, has a high probability that he has a big problem. For example, he is a murderer on the run and it is impossible for him to contact the police on his own initiative. I wonder if everyone agrees with this reverse explanation?" Bai Song looked at everyone and continued, "If he committed the crime, he can commit such a crime and clean up the traces. When Xiao returns in fifteen days, he will definitely close the door and play on the computer, and he will basically be dead."
"Then why did Xiao run away?" asked Captain Zhao.
"This is a miscalculation by the murderer." Bai Song explained, "The murderer originally thought that Xiao would be poisoned quickly and then die at home. According to Xiao's nature as a homebody, no one would know about it until the body stinks. Once seven or eight days have passed, everything in the house will be covered up and the hydrogen cyanide will be gone. If the computer had been running for seven or eight days, it is estimated that this little sodium formate would not be discovered. Moreover, at the high-corrosion scene, our focus may be on the body. This is winter, and it may even take more than ten days for it to be discovered.
After Xiao experienced chest tightness, shortness of breath and other very uncomfortable feelings, he felt something was wrong, so he ran out and went up the hallway, where he fell and never got up again, dying of acute cyanide poisoning. The door was open, so even if there was hydrogen cyanide gas, it would quickly dissipate, and by the time someone found him in the hallway, that is, a few hours later, the hydrogen cyanide gas had already disappeared from the scene.”
Captain Zhao nodded with satisfaction and arranged for people to collect milligrams of white powder and to conduct tests tonight.
"Why would someone kill someone over such a small matter? I really can't understand it." someone asked.
"The suicide case tonight was actually caused by a trivial matter." Bai Song said, "I don't know if you have ever experienced a difficult time. Sometimes when you are having a difficult time, someone provokes you and you even want to kill the other person. It's not common here, but in some areas, there are really murders caused by a sentence like 'what are you looking at'."
"Yes, what Inspector Bai said makes sense. We don't know what the murderer was doing at the time, but it is estimated that he valued the electric car very much or was delayed by something urgent. In addition, as Inspector Bai said, the murderer might be a murderer on the run. He was furious and designed such a scene. This does not require any advanced chemical knowledge, just a clever enough design." The superior expert nodded affirmatively: "I think this idea makes sense. Now that we have so many people, why not check how many households in these communities have lost batteries without reporting the case."
"Okay!" All the teams were ready to go.
This posture gives a feeling of a competition between red and blue.
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