Detective: Start with capturing and retrieving the dog

Chapter 220 Methods of controlling fire

Although the suspect's identity, gender and some physical characteristics have been confirmed from surveillance, there are still many mysteries in this case overall.

For example, when the other party set the fire, whether they used gasoline to increase the intensity of the fire or chose a flammable place to light the fire, and how they found out that the building itself had fire hazards, these will only be known after the police investigation.

At present, the police are already using the figures found in the surveillance to identify nearby surveillance cameras.

This is a lot of work and may take many days to produce results.Before then, the prisoner may have fled to the next city or committed another crime.

Han Xin could only go home and wait for the police's results. By the way, he reminded his parents that this incident happened in Beichang City.

And this time the murderer is even more dangerous than the previous antisocial personalities, because when this bastard chooses his target, he doesn't look at the "victim", but at the "building".

This gym fire alone has caused a large number of casualties. If this guy later finds a building with more people and greater fire safety hazards, it will be dangerous, especially such as supermarkets, department stores, and restaurants. This kind of place.

"That's it, tell your relatives at home not to go to high floors recently." Han Xin warned, "If there is a fire, call the fire alarm first, and then call me to inform me."

After his parents hung up the phone, Han Xin said angrily: "I'm still impatient, as if I want to harm them!"

"I've also told my parents." Zhao Linshan put down her phone and said, "But is it really so dangerous?"

"This bastard is so skilled. He must have been planning for a long time. Then why haven't there been similar cases before? Why did the prisoner wait until now to commit the crime?" Han Xin pinched her face, "It means that something must have happened recently that stimulated his spirit. The incident has made his condition worse, and now his mental state is very dangerous, and he will commit another crime soon!"

"I know, I know!" Zhao Linshan slapped his hand away and muttered: "Be gentle, it hurts."

"Your little face is too tender." Han Xin touched her head and said.

After this, Han Xin began to organize his thoughts.

Since the case happened suddenly and only a little while ago, many clues and details in the case are still being identified, so everything seems very messy.

As long as Han Xin can figure out the logic, the direction of the next investigation will be more specific.

The first thing that can be determined is that the prisoner may be an antisocial personality or have psychological trauma, one or both of these two.He had been hiding well before, but was recently stimulated by something and started committing crimes.

Secondly, the murderer should have a good knowledge of fire protection. For example, at the emergency escape route, Han Xin thought that a place with only walls would not be able to burn. After all, it was all reinforced concrete and there was not much combustible material.

After going to the scene, Han Xin did not see much combustibles, but the flames still spread to the upstairs, which really made him incredible.

Did the prisoner pour gasoline on the scene, or did he use some other method?
He couldn't figure it out, and his "knowledge reserve" couldn't give any hints on such a vague concept.

The next day, when Han Xin brought Zhao Linshan to the Public Security Bureau, the judicial appraisal department also got most of the results.

The person in charge of the appraisal was a sister in her 30s. She looked mature and intellectual, and everyone called her Sister Yang.

"Unfortunately, there is no DNA on the cigarette holder." Sister Yang said expressionlessly. "Preliminary identification shows that the cause of the fire should be that the flame ignited flammable items such as toilet paper in the trash can, and then allowed the fire to spread."

"What about the emergency escape route? There are no tables and chairs over there, right?" Han Xin asked.

"Some grass ash and hydrocarbons were found at the scene. The initial judgment is that there are some paper boxes and plastic bottles piled up there. Maybe they are junk collected by the cleaners and sold." Sister Yang put the question away. Back: "Did you know that the main cause of death in fires is actually the poisonous smoke generated during burning? The burning of plastic bottles will produce a large amount of poisonous gas, and escaping from that kind of place is definitely not feasible."

"How did the flames burn upstairs?" Han Xin asked puzzledly.

"This situation is actually very common, right? When there is a fire on a low floor, the flames will often spread to the upper floors." Sister Yang said with a smile, "Do you know what the chimney effect is? After a fire on a low floor, the temperature rise causes air convection. , the heat wave will rise rapidly along vertical passages such as elevator shafts and corridors. Therefore, the elevator shaft will malfunction first."

"Ah, that's it!" Han Xin suddenly realized, "I thought it was the elevator that the suspect deliberately sabotaged first."

"There is no need, science will help him do it." Sister Yang explained, "Then we know what are the three elements of combustion? Ignition point, combustion-supporting material and combustible material. When the chimney effect occurs, the heat flows smoothly If the temperature is high enough, it will ignite the combustible materials near the elevator upstairs." Han Xin frowned: "Then how to escape from this situation?"

"If the fire on the lower floors is already very big, you can only run upstairs and wait for rescue by firefighters." Sister Yang shrugged. "If you run down, you will die faster. The closer to the burning floor, the higher the temperature." The higher it is, the stronger the poisonous gas is.”

"Oh, no wonder there was a movie called "Escape" before I watched it. It was about a fire in a building, and the people inside ran upstairs after the fire spread. That's why!" Zhao Linshan said suddenly.

"That's right." Sister Yang touched Zhao Linshan's head and smiled.

"Many people don't know this." Han Trust murmured to himself, holding his chin. "After all, people will subconsciously flee downwards when they are in danger on a high-rise. What's more, the fire started on the sixteenth floor, and the eighteenth floor is the top floor. It won’t last long.”

In this way, Han Xin knew why the sixteenth floor, although there was not much combustibles, still sealed people trying to escape inside.

Generally few people know these things, but the suspect does.

"Furthermore, although concrete will not burn, its insulation ability is average, so if the floors below burn vigorously, many things upstairs with low ignition points may spontaneously ignite." Sister Yang said, pointing. Pointing to the top of his head, "Many new buildings now require the installation of heat insulation panels to prevent this from happening."

"When did this system begin?" Han Xin asked curiously.

"If I remember correctly, it should be a rule that started in 06." Huo Gang interjected, "All new houses built after 06 are required to install heat insulation boards, and the previous ones are not necessarily the same. .”

"But ordinary heat insulation boards are useless. They are installed to prevent the heat from the sun's external walls from being transmitted into the house. Their ignition point is not very high, so they cannot prevent a fire of this level." Sister Yang added said a word.

At this time, Han Xin remembered the lighter smoke traces on the top of the emergency escape tunnel, so he asked.

"That is the pinhole camera installed by the suspect. It should be wrapped with fireproof materials, so it can last longer." Sister Yang turned over the report in her hand and said, "But it was eventually destroyed by the high temperature and nothing could be detected. Like. The transmission distance of these devices ranges from tens to hundreds of meters, and it is difficult to find people through this."

"Thank you very much for your advice. Now my mind is much clearer." Han Xin said with a smile.

"If you want to thank him, hurry up and catch him, Detective." Sister Yang pressed hard on his back and said with a smile.

After leaving the appraisal department, Han Xin's thinking suddenly became clear.

In fact, it is not as complicated and difficult as he thought. With the "chimney effect", as long as you light the fire relatively close to the elevator entrance or stairwell, time will do the rest.

As for the building selected by the suspect, although it has fire hazards, no other building can withstand a fire of this level.

"But this makes him more dangerous." Han Xin sighed and said, "This shows that his arson is not that troublesome. It does not take a long time to investigate the scene, and he does not need any special materials to set the fire. He needs Just a cigarette, a few matches, and a building with fire hazards. This guy may commit another crime soon."

"Don't scare me. If we do this again, I'm afraid I will be scolded to death by the superiors." Huo Gang said worriedly.

"But don't worry, I still have some information about the prisoner." Han Xin replied, "Thanks to Sister Yang, we now know that the prisoner is very sensitive to fire hazards. He may have been engaged in fire protection. Or he tried to enter this industry but failed, or he may have been a real estate agent in a community, and his first case was in Yangxiang City..."

Han Xin already had a rough idea. When he returned to the criminal police team's office, he started profiling.

"It can be found from the surveillance that the prisoner is under 30 years old and is from Yangxiang City; he had encountered a fire when he was a child and witnessed someone or multiple people being burned to death; he is engaged in or preparing for firefighting or property work. He used to behave normally, but he may have encountered some changes recently and suddenly disappeared from his circle." Han Xin explained to the detectives at the scene.

"It's hard to find out with these alone." Zhong Li folded her arms and frowned.

Han Xin nodded: "The following is my personal reasoning. Considering that he needs to watch others burn to death to gain satisfaction, I think he planned to engage in firefighting work, and this incident led him to start setting fires and killing people. ', it's very likely that he didn't pass the exam as a firefighter, so his repressed desires completely exploded and made him lose control."

"That is to say," Hu Chen was taking notes on the side, "what we want to investigate is a man from Yangxiang City who suffered a fire when he was a child. He took the fire protection exam but failed, and then suddenly left without saying goodbye."

(End of this chapter)