Chapter 11 third chapter

Under such circumstances, we carefully inspected the scene for the third time, looking for clues. This time I noticed that there was a hole in the wall at the door of the apartment where the petrol can was found. In order to find out whether the murderer used a combustion accelerant, my colleagues and I put some burnt fragments into a sealed bottle and sent them to the laboratory for analysis. Activated carbon is black powdered or granular amorphous carbon.The main components of activated carbon include oxygen, hydrogen and other elements in addition to carbon.In terms of structure, microcrystalline carbon is irregularly arranged, and there are pores between cross-links, which will produce carbon tissue defects during activation, so it is a porous carbon with low packing density and large specific surface area.Activated carbon is also a traditional and modern man-made material. Since its inception for a hundred years, the field of activated carbon application has been expanding, and its application number is also increasing.

I put a piece of activated charcoal in an airtight bottle, took it out overnight and soaked it in a solution of carbon disulfide.Carbon disulfide is a colorless liquid with an aromatic sweetness similar to chloroform, but usually impure industrial products become slightly yellow due to the mixture of other sulfides (such as carbonyl sulfide, etc.), and have an unpleasant smell of rotten radish .It can dissolve elemental sulfur.Carbon disulfide is used in the manufacture of rayon, pesticides, accelerators, etc., and is also used as a solvent. Then, we put the solution in a vial and put it in a gas chromatograph mass spectrometer for analysis.This instrument is characterized by rapid analysis, sensitivity, and high resolution. Even if the amount of sample is small, it can also achieve a wide range of analysis objects, such as gas, liquid, and solid organic samples.In this way, the separation and identification of complex organic mixtures can be quickly and simultaneously completed at one time.Therefore, chromatography and mass spectrometry have become the most mature and effective analytical tools for organic mixtures.

When I use this instrument, of course I also know the method very well.Mass spectrometry is a modern physical method. Its working principle is to first split the gaseous substance molecules into ions, and then separate the ions according to their mass. After the detection and recording system, the mass-to-charge ratio and relative intensity of the ions are obtained. A spectrum, also called a mass spectrum.The mass spectrum provides us with important information about the molecular weight and elemental composition and molecular structure of the substance, so that we can identify the molecular structure of the substance.

The instrument separates flammable liquids contained in samples based on their physical and chemical properties.Each of the liquids in the sample flows through the instrument at different speeds, which separates them.Moreover, the composition of flammable liquids can be seen at a glance. The test results confirmed that the murderer was the fire ignited with gasoline.Obviously, the gasoline was ignited and caused an explosion. As a result, a hole was blown in the wall of the door. We also found a book-style matchbook among the ruins, folded into a small, cardboard-like tri-fold.Only fire can ignite gasoline, and the match cardboard we found at the scene of the fire looked new, with only one match missing inside.But that doesn't explain anything either, as no fingerprints were found on it.

While my colleagues and I were busy at the scene, Inspector Harry was in his office poring over photos of the fire scene, looking for information that might have been overlooked.This is how we recorded the location of the case and the apartment where the criminal traces and physical evidence were left in the process of using criminal photography. The location of these items, etc., have been photographed one by one truthfully. These photos can provide information for studying the nature of the case, analyzing the means of committing the crime, conducting on-site experiments, and providing conditions for technical inspection and identification.At the same time, these photos can also provide evidence for prosecution and trial.

Inspector Harry carefully checked the photos one by one, and he would not ignore any doubts.On one of the photos, he saw something that looked like glasses. After I received Harry's call, I found a pair of glasses at the scene according to the location he pointed out. This is obviously a pair of myopia glasses. I hope to find its owner through the optometry record of the optician.If the glasses didn't belong to the college student or the victim, they must have been left by the criminal. Harry also found a well-preserved cigarette butt through the photos.The cigarette had obviously been smoked, but it wasn't snuffed out or stamped out.The cigarette butt was still burning when it fell on the carpet, because there was no pressure indentation at the end of the cigarette butt, and it kept that round shape.

We suspect the murderer had lit a cigarette and then picked up a petrol can and dumped it around the apartment.Somewhere, the criminal lit the gasoline with a cigarette butt.I went on thinking about these very small details, fearing that I might miss it. According to Harry's analysis, it is very likely that the sudden flames burned the criminal's nose.This shows that the criminal still lacks common sense in this area. He didn't know that the flammable gas volatilized from gasoline had filled the air at that time, so he slapped the fire vigorously, but knocked off his glasses in a panic. It also fell from his mouth to the ground.

The criminal didn't want to leave the evidence at the scene, but he wanted to return. It would not be so easy to get it back, because the fire had started to spread, and he had only one way to go at this time, and that was to escape.As for the distance between the place where the criminal ignited the gasoline and the hole at the door, we can use the measurement results to illustrate the problem, which leads to two possibilities: one possibility is that the criminal must first find the place where he ignited. The retreat route, if the criminal does not grasp this route well, then the criminal himself may be burned to death; another possibility is that we should judge the size of the opening of the door wall to understand the degree of force on it. If it is opened, it will be large, otherwise it will be lightly stressed, that is to say, the position of ignition will be basically clear.

However, my analysis is like this, if we use a line to connect the place where the oil barrel is placed, the opening of the door wall, and the door of this room, we will find that it is a triangle.I judged that in this triangle, it might be the place where the criminal lit the fire.Before the criminal lit the fire, he had to think about his own life first, so he had to think about his escape route first, and get closer to the door.Perhaps, the criminal has thought about the escape route after lighting the fire a thousand times or even ten thousand times, but there are still many problems exposed in the process of lighting the fire.

I have seen the mode of operation of criminal arson.Suppose, what kind of psychology does the criminal have when he puts the two corpses in two different rooms?In fact, he could have burned the two bodies in the same room, thus creating a scene of two people being burned to death.The room I mentioned was the one facing the road, but the criminal didn't do that. What was he thinking at that time?At that time, he was thinking about how long the retreat route would be after he finished lighting the fire, and how to determine this line. He knew very well in his heart that he would not put his life on it.In this case, he will have to repeatedly consider whether his arson plan is feasible.Of course, the basis for this plan is after the death of two women.Before the two women died, the criminals may have had another arrangement that had nothing to do with arson.I think the other arrangement failed, which made him change his plan.In other words, there is an inevitable connection between the two arrangements.

Because the crime scene is a university apartment, there is no very lively place near this apartment, which has a lot to do with the lifestyle and habits of the university.It can be said that this apartment is very secluded, so it can be seen that the criminal has already made a choice in his mind about the location of the crime, which is why he brought the two women here.He could have taken the two women to a friend's house or to his own, if the two women wanted to, he could do it. Next, I will analyze why the criminals separate and burn the two female corpses. This seems to be an accidental problem, but what it reveals is its inevitability.The reason why I use the word "necessary" to explain it is because after the criminal killed the two women, time forced him to respond quickly, which is how to deal with the two bodies.Time is running out for the criminal, then, because college students are coming back and St. Patrick's Day celebrations are coming to an end.To be precise, it will be over in the second half of the night on March 17. Once the event is over, many people will return to this apartment, including the owner of this apartment. At this time, the criminal was very confused. Since he could not transfer the corpses, he could only burn the apartment to create the illusion that the two female corpses were burned to death. This is the most direct and simplest way.Therefore, the criminal needs to prepare gasoline. Whether he can smoke or not occupies a very important position in the whole case. To use it as a basis for arson, but to achieve his purpose of destroying evidence by burning corpses and destroying traces. The gasoline barrels chosen by the criminals are mainly bright in color, so that they can hide the eyes and ears.He wants to avoid people's suspicion of what he is carrying by the unusual color and shape of the barrel.On the street, people saw him carrying something like a vacuum cleaner. Who would doubt a cleaner or a manager walking into an apartment during the day with a vacuum cleaner?Next, the criminal should choose at night, or choose a time when people are not paying attention, and he will bring the gasoline can into the apartment.Then, he was about to set fire to it. At this time, the criminal continues to consider the next course of action.He wants to implement the plan, which is to set fire, and use this to fake the scene.However, the criminal encountered a difficulty in implementing the plan, that is, the method of arson and destruction of the corpses. He seemed to have considered for a long time, and finally came up with this method, which is the separation of the two corpses we saw at the scene. The location, as well as the distance of separation, can also infer the psychological characteristics of the criminal at that time.He must protect his own safety first, and then ignite the fire. The criminal was very clever. He put a dead body in a room inside, and then put another dead body in the living room, and it was very close to the door, which was for retreat.When the criminal pours gasoline on the ground, the action should be to pour it while walking slowly backwards. When he retreats to the door, he will start to ignite the fire.At this time, he didn't know the truth that igniting gasoline with a match could cause the gas volatile in the air to cause an explosion, and gasoline must never be placed near an open flame.He thought this truth very shallowly, and half understood a buffer idea, that is, he would use a cigarette to ignite the gasoline after pouring the gasoline. While the criminal was pouring gasoline, at the same time, the volatile concentration of gasoline in the air gradually increased, which was a potential threat to him.But he left the door open, already thinking that if the fire was lit, he could exit that living room in seconds and be gone. At this time, the criminal finally retreated to the door, indicating that he had finished pouring gasoline.So he put the barrel on the right side of the door instead of the left.It can be seen that criminals are used to carrying things with their right hands rather than left-handers. Next, the criminal started to light a cigarette with a match. The posture should have been like this. He held the cigarette in his right hand and slowly touched the cigarette butt to the ground.At this moment, there was a sudden bang, and the flames sprang up immediately. He couldn't control the sudden fire. Without any preparation or response, the first thing he thought of was how to escape safely.This can be said to be an inevitable reaction in desperation. His glasses fell on the ground at this time. When he wanted to pick them up, it was too late. The fire had already started, so he turned around in a panic and ran for the door. , disappeared into the night.It should be midnight by this time, and many people are about to rest.Unfortunately, the fire was discovered by a passerby. As for the time of arson, it also fully demonstrated the wisdom of the criminals, that is, to choose the time of arson at midnight.Perhaps the criminal is very familiar with the situation in this area. I concluded from the apartment the criminal chose. The criminal's familiarity with the environment has far exceeded our imagination of him, because he is too precise, he can Know which apartments are occupied and which are not. Well, there is such a problem.How did the criminal know that this was the one room in the apartment that hadn't been occupied recently?How did he get this information?If someone told him, then who is this person?Is it his accomplice?Or someone else who committed misdeeds?Is it normal for people who commit misdeeds to appear near the university?If it is abnormal, what kind of people should those people be, are they students?Students come here mainly to study, among these students, it seems that there are very few people who have misdeeds. The reason why I say "rarely" is that a university is a place for education, and its perfect hardware facilities can also play a role in purifying the soul. If this case is really committed by a college student, then this college student Is it just to set fire to come here to study?Obviously, this can rule out the possibility of college students committing crimes. Now let's analyze again. When a person has a tendency to violence, he will show it in actions and words.Where does this tendency come from?If such a violent tendency is interpreted as a kind of hatred, then in this case, this assumption is a bit unreasonable, because the criminal and the two dead women did not know each other before their death, let alone familiarity. There is no hatred.There are two possible reasons why this criminal wants to kill people who have nothing to do with him: one is for money, and the other is for sexual desire. Both of these are unlikely for the students of the University of Iowa, because they There is no need to get money by robbery, let alone rape and murder to vent one's desire. Let's think about it from another angle, since this case was not committed by college students, then who could have committed it?Who on this university campus is most likely to commit this type of violence other than college students and school staff? My analysis made all the agents ponder.Harry took my word for it, saying: "The culprit would be a tall, shaggy-haired, smoking man with probably burns on his face and maybe he lost a pair of glasses." "Yes, a criminal should have messy hair," I said, "with messy hair like this, we call it slovenly, and does this kind of person exist in this university? I think a criminal should be a social loafer." personnel." Near the University of Iowa, there is an idler who is very familiar with the apartment situation.He can know exactly which rooms in this apartment are occupied and which rooms are not occupied. It is as if the criminal has been in the dark and can see everything about us very clearly.We finally figured out a relatively clear thread about the arson case.