The concept of the cost of killing was proposed by a foreign economics professor, and in his opinion, everything in this world seems to be linked to the economy.

At that time, many people felt that what he said was a bit exaggerated and very unrealistic.

At the scene, I thought that the police, and at that time I gave an example, that is, their police station, there happened to be a case, the murderer threw the body into the river after killing someone, and then the police found the suspect in a bar by the river, but he had alibi evidence.

The other person has no alibi at all, and lives in a small apartment, both of whom are now suspected, but the police have no way to conclusively determine who is the murderer.

After this problem was thrown, there were not many people who came to the class, but because of this problem, his public class became extremely popular.

It's not because of anything else, the main reason is that after analyzing the income of two people in an open class, he directly pointed out the real culprit of this case.

After checking, faced with a list of accounts taken out by the professor, the murderer actually admitted the fact that he committed the crime.

In fact, the reason is very simple, this professor started with a complete economic accounting, analyzed the income of two people, and the monthly expenditure, and compared the two, after comparing the cost of this murder case, he easily found out the suspect.

In principle, it is not very difficult, but this kind of large amount of data calculation has become a relatively difficult problem to overcome.

However, there is one thing that Ding Fan still admits, that is, there are often a lot of flaws in cases where the cost of crime is too low.

Ding Fan used this method to analyze the position occupied by Ma Lu in this case to a large extent, after all, Ma Lu has no income, he begs outside for a maximum of one or two yuan a day, and he can't save this money, otherwise there will be no time to ask Uncle Lu for food if he can't eat.

And the deceased Zheng Nancheng, the cost of death required is a bit high, at least the purple flames burning on and around the deceased, this thing is not something he can handle.

So it is impossible for this person to kill people at all: "Before Zheng Nancheng died, did you sleep on the third floor?"

Ma Lu glanced at Ding Fan and nodded a little nervously.

But soon explained: "We lived together before, both on the second floor, and there was a conflict in those two days, so we separated, and at that time I heard a noise downstairs, as if someone was laughing, and I thought he was crazy." ”

"He hadn't laughed like that before, it sounded like a nervous break, and I was a little scared, so I went down from the upper floors to have a look. ”

"When I got to the top of the stairs, I found a fire below, and I thought he was going to commit suicide, and even wanted to die with me, so I took a sneak peek, and found that he had fallen to the ground, covered in blood, and a man in black clothes was squatting beside him, his hands were covered with blood, and I couldn't control my feet at that time, and my legs fell down as soon as I went weak. ”

"The man must have spotted me, and rushed straight at me, I wanted to run, but I didn't have the strength to do it, so I rolled down the stairs. ”

"By the time I got up, he didn't know where to run!"

Ding Fan sat on the side, holding the pen in one hand and pressing the notebook with the other, his hands slid quickly, and finally turned the notebook and stood in front of him and asked, "Is this an action?"

Ma Lu looked up and saw that this image was what he saw at that time, and he was immediately startled and nodded quickly.

The sketch drawn by Ding Fan is very detailed, it is the picture I saw in the game hall before, the character called Yagami An, squatting on the ground and frantically tearing the opponent on the ground.

The opponent's abdomen was torn to pieces, and then his hands smashed into the deceased's body with purple fire.

To be honest, this scene left a deep impression on Ding Fan at the time, especially the rampant smile that Yagami Nunnery turned around at the end, I am afraid that many people will remember this scene.

And what Ma Lu saw at the time turned out to be a live-action version, so it is not surprising that he was paralyzed by fright.

"Tell me more about that person's appearance and figure!" Ding Fan returned to the side, opened a picture book again, and asked, "Height, body shape, in short, everything you can think of." ”

"Actually, you should know very well that the murderer has seen you, and he knows about your existence. ”

"And your existence, for him, is not a good thing, as long as you are alive, he will not feel relaxed, you are likely to become a target for him, you don't want to die you better be more careful, at the moment you are the only one who has seen him, and he can still survive. ”

Of course, Ma Lu knew this, but he didn't have a clear memory of the person at that time, after all, that person had so long hair......

"I remember, that person's hair is very long, it can cover half of his face, and he has red hair!" Ma Lu also inadvertently remembered this, and he didn't know if these were useful, so he hurriedly told Ding Fan about it.

However, Ding Fan seems to have thought of this before, in terms of cost, the cost of dyeing his hair is not very high, and the murderer wants to imitate all the details of the murder of Yagami An, so naturally he will not give up this key point.

And Ding Fan could even imagine what kind of clothes he was wearing when he killed people at that time, and the huge moon wheel symbol behind him was naturally indispensable.

"Details, details and other things, how many have you seen?" Ding Fan frowned a little and kept reminding: "Hair is such a thing, just dye it, or simply cut off all the hair, this is not a useful clue, useful refers to whether he has a scar on his hand, or a lack of fingers, walking slopes and other things that have no way to hide." ”

In fact, Ding Fan's guidance has already told him everything he can say, and if he continues to talk about it, he will be suspected of inducing a confession.

It's a pity that the road didn't see these things, and carefully recalled them for a long time, and finally shook his head and didn't think of anything useful.

But there is one thing, Ding Fan did not guess wrong, the murderer's height is about 1.6 meters, and his figure is a little fat, just a five-short figure.

Unfortunately, there are no other useful clues.

For the interrogation of the road, the effect was not very great, Ding Fan simply categorized it, and left first with the things in his hand.

Zhu Zhenyu followed behind him, and he was also full of curiosity about what he painted.

It's just that after Ding Fan showed him, Zhu Zhenyu was stunned for a moment, and hesitated for a long time before he spoke: "Isn't this a character in the game?"

It seems that this game is really popular!

Except for Ding Fan, almost everyone knows it, and looking at his appearance, you can know that he knows a lot about the things in it, and eighty percent of them have played it before.

"I now suspect that after playing the game, this murderer has a wrong perception of this character!" Ding Fan stood on the façade of the corridor, chewing gum in his mouth and said: "I liked this character from the game, and then he had a feeling of sympathy for this character, and even linked it to himself, feeling that he was this person, and he had a kind of mental confusion." ”

"Isn't that a neurosis?" Zhu Zhenyu thought for a while and said in surprise.

However, Ding Fan shook his head, glanced at the figure in his hand and said: "It's not neurosis, but it's more terrible than neurosis, you can see some neuropathy from the appearance, but his paranoia is completely invisible, he usually looks like a normal person, no matter how you look at it, you won't feel that there is anything abnormal about this person." ”

"As soon as the person is stimulated by the outside world, or just sees something, he will enter another state, which you can also understand as a split personality. ”

"In a person's body, there are two souls, and the two souls are completely independent, and they know that there is another self in each other's existence, but what the other self has done, they themselves often do not know. ”

Zhu Zhenyu had never heard these words before, and he was so frightened that he trembled when Ding Fan said this.

After all, his description is really a bit scary, there is a soul in a person's body, isn't this the ghost upper body in folklore?

This kind of thing has never had a scientific basis, but now that Ding Fan said this, this kind of thing has often happened before, and this murderer is definitely not the first one.

"You can think about it, one is from the perspective of a normal person, and the other is from the perspective of a normal person, and the other is a person from that storyline!" Ding Fan thought for a while, and planned to explain to him about this split personality.

But before he finished speaking, Qin Lu came over from outside and said loudly to Ding Fan: "I made the purple flame, do you want to take a look!"

I really didn't expect that this wife was so reliable, she thought of everything Ding Fan thought of, and even the purple flame came out.

I thought I was going to go to the inside of the dissection room, but who would have thought that Qin Lu would take Ding Fan directly outside and use some dry branches to light a bonfire on the ground.

Many people were watching from the outside, thinking that they were planning to have a bonfire.

Who knows, after Qin Lu came, he took out a small paper ball from his pocket and threw it into the middle of the flames.

The flames on the ground crackled, and the paper balls were quickly burned out.

Ding Fan glanced at Qin Lu beside him a little embarrassed, obviously afraid that Qin Lu's experiment would have an accident, and would it be a little embarrassing at this time.

But before he could speak, the bonfire on the ground instantly turned purple, accompanied by some crackling sounds, and the flames danced with this color, which looked extremely weird.

"Actually, it's not difficult, I already thought of this structure in the afternoon, but I don't know the ratio!" Qin Lu stood beside Ding Fan and said a little proudly: "You should have seen fireworks, that thing has any color, just because potassium salt is added to it, but this ratio is a little difficult, I thought about it for a long time to get it." ”

It's a shame that Ding Fan thought about it for so long before, and wondered if there was any clever way to make the flames purple.

After a long time, it was a fireworks effect.

But is there a fireworks factory in Pengcheng?

The larger fireworks factory doesn't seem to exist at all, but I don't know if this small workshop will have one.

"I'm giving you the latest news, the time of death of the deceased has been determined, one o'clock in the morning!" Qin Lu looked at the bewitching fireworks on the ground with an expression on his face and said: "It should be able to judge from the time, the time when the murderer left the city, there is surveillance on the way out of the city!"

This point, in fact, Qin Lu doesn't need to say it, Ding Fan can also guess it, but it's useless to check this monitoring, the murderer must know that there is monitoring, he will choose to go out of the city when there are more vehicles, and wait until late at night to do it, this clue does not play a big role.