Chapter 55 Chapter Fifty-Four

Gao Dong's attention was attracted by a photo of footprints on the hillside. There was a footprint on the edge of the photo, and a straight strip was embedded in the middle of the footprint. It's the rope! At that time, the murderer stepped on a piece of rope under his feet. He hurriedly put together all the photos on the hillside and checked them carefully. After searching for a long time, he didn't see anything like abandoned ropes on the hillside. He looked at each footprint again, and finally, in an inconspicuous corner of another photo, he also found evidence of stepping on a rope under his feet.

The murderer used the rope!However, the police did not find the rope at the scene, and it can be seen that the rope was taken away by the murderer. Gao Dong quickly picked up the phone and called Chen Forensic Doctor to his office, pointed to the photo and asked him, "What is this?" Chen Fayi looked at it for a moment, and immediately said, "It should be a rope." Gao Dong nodded: "In terms of shape, it is about a fiber rope with a diameter of no more than 1 cm. Did you find any leftover rope fragments at the scene?" Forensic Chen shook his head: "No."

Gao Dong pointed to another photo: "If you look at this one, there are also rope marks. You didn't find the rope at the scene. The footprints in the photo have stepped on the rope. Where did the rope come from? It can't come out of nowhere, showing that The murderer brought a rope and stepped on it while walking. But we didn’t find the rope at the scene afterwards. What does it mean? It means that the murderer took the rope away from the scene again. Why did he do this? The answer can only be The rope is his tool of crime!" Forensic Chen thought for a moment, and then questioned: "The suicide scene was faked with a rope. There were only footprints of the murderer on the hillside. Shao Ju did fall from the hillside and fell to his death. Then there is only one result. The murderer tied Shao Ju's uniform first. Finally, put it on the stone beach under the cliff, climb up the hillside, throw the rope from the hillside, walk down the hillside to the stone beach, tie Shao Ju with the rope, and then return to the hillside again, throwing people away. Pull it up 20 meters, and after pulling it to the hillside, untie the rope and let people fall naturally."

Gao Dong nodded: "The footprints on the mountain can be judged. The murderer has gone up and down the mountain, and it happened several times. Why did he go up and down the mountain many times? It's because he couldn't complete Shao Xiaobing's suicide in one go. Back and forth many times." Forensic Chen said: "But this method is different from the weight of the footprints. Shao Ju weighs more than 160 kilograms. Not only can one person pull it at all, even if he can pull it, the combined weight of the murderer and Shao Ju will stay on the hillside." The weight of all the people on the footprints is probably about three hundred catties, which is inconsistent with the identification results."

Gao Dong frowned and pondered: "This is a difficult problem. By the way, is there any way to forge the weight of the footprints? For example, the actual weight is 300 catties, and through some method of falsification, so that your identification results show that the weight of all the footprints is the same. Between one hundred and forty-five and one hundred and sixty-five catties, which is equivalent to half of it?" Forensic Chen shook his head: "Impossible, unless he has four legs." Gao Dong kept his mouth shut. There are no four-legged people in the world, which shows that his deduction is wrong.

Forensic Chen thought for a while, and then continued: "I think the key issue is not the weight of the forged footprints, but how the murderer pulled Shao Ju up. No one can lift the weight of more than 160 catties, let alone pull it up two years ago. It's more than ten meters." Gao Dong sighed: "Yes, if Shao Xiaobing is not a fat man, he might still be able to move a hundred catties—wait a minute," Gao Dong suddenly stopped talking, and after a while, he opened his eyes and said, "If Shao Xiaobing is not a fat man, if Shao Xiaobing is not a fat man! The rope, the iron hook—”

"Boss, what did you think of?" "I thought of a way that is feasible. By the way, what is the name of a master's degree in structural mechanics that you got admitted last year in the Department of Biological Sciences?" "It's Guo Jie." "Yes, that's Guo Jie, you call him over." "Call him? He was the first recruit in the public examination. He has only worked for more than a year. He lacks experience and professional ability. I contacted the school to do the footprint identification work. It has nothing to do with him." Gao Dong nodded again and again: "I know, but he is the only one with a background in mechanics here. Call him quickly, I have questions for him."

Soon, Forensic Chen came in with a young policeman wearing black-rimmed glasses and a nerdy face. Gao Dong immediately asked, "Xiao Guo, you study mechanics, right?" This little policeman with the youngest qualifications in the Physical Appraisal Department has never spoken to Gao Dong since he was a police officer. Now Gao Dong personally called him to question him, and replied with trepidation: "My undergraduate degree is in civil engineering, and my master's degree is in civil engineering." The direction is structural mechanics, and I was admitted to the civil service last year."

Gao Dong said: "Okay, I will give you the title of debut. Now you are standing on a cliff 20 meters high, and there is an object weighing 160 kg under the cliff. You have a rope. How can you get this object?" Pull it up?" Guo Jie thought for a long time, then cautiously said: "Straight... can't you just pull it up?" Gao Dong immediately looked disappointed, Chen forensic doctor glanced at his mouth, you can pull a hundred and sixty catties, do you think you are a crane?This guy has a bookish face, and he's here to be a criminal police officer? Gao Dong smacked his lips, controlled his emotions, and said, "Brother, you can't lift something weighing one hundred and sixty catties."

Guo Jie's face was flushed red, he thought for a while, and said: "Just...just rely on a rope to pull it directly." Gao Dong said: "In addition to the rope, you can add other tools, except mechanical equipment." Guo Jie immediately replied: "That's easy, use a pulley device." "Pulley device?" Chen Forensic showed surprise on his face. Gao Dong seemed to have expected everything, smiled with satisfaction, and said, "Go ahead." "Just one movable pulley can reduce the required force by half, which is 80 catties. Of course, if you add a fixed pulley, that is to say, the combination of a fixed pulley and a movable pulley can reduce the force by one-third , which is equivalent to only needing to pull more than 50 kilograms of force."

Gao Dong picked up a pen and handed it to him: "Draw the combination of movable pulley and fixed pulley you mentioned on the blackboard." Soon, Guo Jie finished drawing on the blackboard, Gao Dong nodded with a smile, and said, "Alright then, you can do your work first." After sending Guo Jie away, Gao Dong and Chen Forensic looked at the pulley device on the blackboard. On the blackboard, an iron hook hangs a fixed pulley on the top, and a movable pulley is below the fixed pulley. A rope is drawn from the center of the movable pulley, which goes up around the fixed pulley, then down around the movable pulley, and finally pulls up.Below the movable pulley, a heavy object is hung, which is equivalent to the weight being pulled by three ropes at the same time, and the force required by each rope is only one-third. In this way, only one-third of the effort can be used to pull up Shao Xiaobing, a fat man who weighs more than one hundred and sixty catties. Gao Dong looked at Chen Fayi with a smile, and said, "How about this method?" Chen Fayi nodded repeatedly, and took the opportunity to flatter him: "Boss, why did you think of this? It's amazing." Gao Dong said: "Inspired by what you said just now, the key problem is not how the murderer faked the weight of the footprints, but how he could lift Shao Xiaobing, who weighs more than 160 kilograms, by 20 meters. A rope was found in the photo There is an iron hook nailed on the edge of the cliff, and I naturally thought of the pulley device I learned in middle school. But it has been twenty years, and I have almost forgotten it, so I can only call the bookworm below you to ask carefully. " Forensic doctor Chen said: "This method is indeed feasible. I have been a police officer for decades, and I have never seen such a scene of suicide planning." "Let's check the photos again. If the murderer really used this trick, maybe when he installed the pulley, he put the pulley on the ground, which might leave indentations." Soon, the two carefully searched for the traces in the photos. In a photo next to a cliff, they found a very small and shallow arc-shaped indentation.If they didn't think of pulleys and looked for such indentations in a targeted manner, they would never notice such shallow and short marks. Chen Fayi looked at the photo and said: "The indentation is very shallow, and it is impossible to tell whether it was made by a pulley." Gao Dong said: "The arc of the indentation is very smooth. It should not be left by removing the stone, but a pulley. If this is the indentation left by the pulley, then the diameter of the pulley is about 20 centimeters. The hillside is 20 centimeters high. Duomi, he uses a combination of fixed pulley and movable pulley, the force used is one-third, and the length of the rope required is three times, that is, the rope is at least 60 meters long." Forensic Chen nodded. Gao Dong continued: "Let's calculate the actual weight of the murderer. The murderer stood on the hillside and pulled the rope, and it took more than 50 catties to pull Shao Xiaobing. The murderer should have pulled the rope against the fixed pulley on the iron hook." Yes, the applied force is obliquely downward, rather than a complete vertical force. In other words, part of the weight of more than 50 kilograms is distributed to the horizontal force, and part is distributed to the vertical force, forming the weight of the footprint. From Judging from the angle of a normal person standing on the mountain and pulling the rope, the force of more than 50 kilograms is divided into the vertical force, which is about 20 to 30 kilograms. The weight of the footprints you identified minus 20 to 30 kilograms, I guess the murderer The actual weight may be around one hundred and thirty catties." Chen Forensic Doctor nodded and said, "As for the other footprints, the weight matches Shao Xiaobing's weight, because when the murderer went up the mountain, he carried the weight of pulleys and more than 60 meters of rope." Gao Dong said: "Then, have you ever thought that the murderer was carrying something when he went up the mountain, and the weight test results were consistent with Shao Xiaobing's, but he didn't carry things all the time, why the weight test results of all the footprints were basically the same Woolen cloth?" Chen Fayi thought about it, shook his head in confusion, and said, "This is a contradiction." Gao Dong said: "This shows that after the murderer put down the pulley and rope, he must have picked up the stones beside him to ensure that the weight of all his footprints was basically the same." Forensic Chen opened his mouth wide in surprise: "This... can you think of this? What kind of murderer is this?" Gao Dong continued: "The murderer chose the place where Shao Xiaobing committed suicide. He did not choose any other place, but chose here because the footprints here can be best preserved, so that we have enough evidence to determine that it was a suicide. He deliberately put the footprints Leaving it to us is naturally taking into account the various identification work that our police will conduct on the footprints. The identification work is nothing more than height, weight, etc. He must want to get it." "But as for the shoes, the murderer wore Shao Ju's shoes to complete the suicide arrangement. He finally went down the mountain wearing Shao Ju's shoes, and the shoes did not fall from a height of more than 20 meters. But the shoes we found, obviously It was broken." Gao Dong didn't take it seriously, and said, "When you saw the corpse, were the shoes on Shao Xiaobing's feet?" "That's not true. The shoe fell aside and broke." "That's fine. After the murderer killed Shao Xiaobing, he continued to wear his shoes, took a pulley and a rope down the mountain, came to the stone beach, then took off his shoes and threw them on the cliff a few more times, and finally threw him next to Shao Xiaobing's body. Let us judge that Shao Xiaobing fell off the cliff when he jumped off the cliff. The stone beach has the advantage that no footprints can be left, and after the murderer is done, he can go directly into the sea and go around without leaving any footprints." Forensic Chen nodded again and again. According to Gao Dong's method, the questions on the beach can basically be solved. Gao Dong picked up the phone, called Jiang Wei, communicated the analysis results with him, and ordered him to immediately send someone to investigate the time before the Shao Xiaobing case, which store in the county sold at least 60 meters Long rope, and has anyone bought a pulley lately. Gao Dong knew that Ning County was a major coastal fishing county. Ropes and pulleys of this diameter were used a lot on fishing boats, and there were also many shops of this kind. It would take some time to investigate, but now this is the most direct way. After sending the two away, Gao Dong sat in a chair and reorganized his thoughts. The murderer's height is between 171 and 175, and his real weight is about 130 kilograms. According to the monitoring, he is a middle-aged and young man, and his exact age is unknown. In Shao Xiaobing's case, although the murderer unbelievably used a pulley device to create the illusion of suicide, his details could not be 100% perfect.For example, he stepped on a rope under his feet, and when he put the pulley on the ground, it left a small arc of indentation.Of course, if he hadn't thought of the pulley device, Gao Dong would have thought that a stone had been kicked away from the small indentation, and would not have paid any attention to it. The process of Shao Xiaobing's fake suicide is basically clear. The murderer probably controlled Shao Xiaobing first, probably by binding him. Old Chen said that Shao Xiaobing had a contusion on his wrist, which now seems to be caused by being tied up, not by falling.After the murderer tied up Shao Xiaobing, he put him under the cliff, and then came to the hillside, hung the pulley and let down the rope.In order to keep his weight basically the same, the murderer picked up the stone beside him, walked down the hillside, returned to the cliff, and tied the rope to Shao Xiaobing.Back on the cliff again, after pulling Shao Xiaobing up through the pulley device, he untied the rope and let him fall freely.Finally, pack up everything, take things and leave. If the script is really written like this, then there is an explanation for Shao Xiaobing's car appearing one kilometer away in the end. Two pulleys and a rope at least 60 meters long. This pile of things could not have been carried by the murderer. The murderer must have taken it from Shao Xiaobing's house, after controlling Shao Xiaobing, and driving from the county town to the beach.It has been analyzed before that the murderer has a car, so the murderer must have put these criminal tools in the car in advance, drove Shao Xiaobing's car halfway from the county town to the beach, drove to his car and stopped, got off to get the criminal tools in his car .Then continue to drive Shao Xiaobing's car to the beach. After arranging everything on the beach, the murderer left the scene with a pulley and a rope. If the murderer's vehicle had been parked near the beach in advance, he didn't need to drive Shao Xiaobing's car, he just took the criminal tool back into the car and left.The murderer must have thought that the car parked in this desolate place nearby would be easily remembered by passers-by, so the car was parked far away from the beach, probably on the road of the county town. Because the murderer's vehicle was far away from the beach, the murderer couldn't walk back with so many pulleys and ropes, so he got back into Shao Xiaobing's car and drove away one kilometer away. However, the location of the village is the opposite of the route when they came, which proves that the murderer's car is not near the village. Then the murderer naturally wouldn't carry so many things and walk back to the car from the village. If all this reasoning is correct, sure, the murderer must have left the tools of crime near the village! The police investigated the village the next day after the incident. The murderer should not dare to go back to the village to take away the criminal tools, because doing so would be very risky. Gao Dong thought about it, and immediately decided to send someone to the village to inquire carefully, and search carefully around the village. As long as the criminal tool is found, then all the reasoning will be complete. He thought over the murderer's entire crime in Shao Xiaobing's case, and the murderer's handling of the details of the crime was impeccable.For example, after hanging pulleys and ropes on the hillside, the murderer would even think of picking up the stones next to him and going down the hill, so that the weight identification results of all his footprints were basically the same. But he has calculated everything, and during the actual operation, at least more than 60 meters of rope was still accidentally stepped on. This is the only flaw, but this is the breakthrough! His thoughts returned to the case of Hu Haiping being crushed to death by a stone slab. Although Gao Dong hadn't figured out how the murderer controlled the slate to fall, it was clear that the time when the slate fell was accurately calculated. One is a free fall and the other is a pulley device. Gao Dong's eyes flashed coldly, the murderer's knowledge of physics and mechanics is really solid!