Attending ex-girlfriend's wedding, arresting the groom's officer on the spot

After saying goodbye to Aunt Li, Wang Shuai and Zhang Hui visited the security guards and neighbors in the community. In the security room, they carefully checked the surveillance video, starting at 12 o'clock that night, and checked it frame by frame. "Pay attention to this man in a black cap." Wang Shuai suddenly pointed at the screen, "At : last night, he came out of the fire escape of Building , holding a large travel bag in his arms, and his walking posture was a bit stiff, which was very suspicious."

Back at the scene, Yang Sen and Yang Lin continued their investigation. Yang Sen lay on the ground and carefully observed the blood on the floor with a magnifying glass: "There are signs of dragging here, extending from the body to the French window." He checked the lock of the window again, "There are no signs of prying on the lock, but there is a half-broken blood fingerprint in the gap of the window, Yang Lin, prepare to extract it."

Yang Lin took out the fingerprint extraction kit, first brushed the magnetic powder evenly on the fingerprint area, then carefully extracted the fingerprint completely with transparent tape and attached it to a special fingerprint card. The whole process was smooth and every action strictly followed the criminal investigation standards.

After Yang Lin and Yang Sen had basically completed some details of the on-site investigation, Lu Chuan came out of the door.

Lu Chuan put on blue shoe covers and crouched over the cordon. Under the cold white light of the investigation lamp, the bloodstains in the living room looked like a hideous abstract painting, with the solidified dark red spreading from the Persian carpet to the off-white wall. Yang Sen half-knelt beside the corpse, the scale held by the tweezers at a 45-degree angle to the ground, and the metal reflection reflected his focused profile.

"Let's see if we can restore and reconstruct what happened at the crime scene based on the bloodstain spray and its characteristic details."

This crime scene was somewhat different from the murder scenes that Lu Chuan and others had encountered before in that there was more blood spurting, and the cause of death was most likely ischemic shock caused by the knife wound.

We still have to wait for the results from the forensic department, but the blood splatter caused by these knife wounds can actually provide the police with a lot of information to solve the case, such as the direction of the blood spray, the direction of the obstruction, the angle of the blood spray or the height of the drop, which can determine some characteristics of the suspect, such as height, strength, whether the other party knew the deceased, whether there was a conflict, etc., and can make some simple judgments.

"The first spray point is here." Yang Sen pointed the tip of his pen at the fan-shaped bloodstain 1.7 meters above the wall. "The spray angle is 32 degrees, which is consistent with the trajectory of a right-handed stab from bottom to top." He turned to look at Lu Chuan, his eyes revealing excitement under the protective mask. "The murderer is at least 175 cm tall, and he used a lot of force when swinging the weapon."

Lu Chuan followed the bloodstains to the French window, the rubber soles of his shoes making a slight friction sound on the floor. "Pay attention to these drag marks." He squatted down, and the red dot of the laser pen jumped on the ground. "There are five parallel bloodstains from the body to the window, with a spacing of 15 centimeters, which means that the deceased tried to crawl to the window for help after being stabbed."

Yang Lin held the 3D scanner and walked around the venue. The humming sound of the equipment mixed with the sound of the air conditioner. "The blood stains on the wall are distributed in an irregular ellipse, and there are obvious splash burrs on the edges." He called up the modeling image on the computer. In the virtual scene, the red blood stains spread like ripples. "The fatal injury should be in the heart. The pressure at the moment of blood spraying caused the blood droplets to splash onto the ceiling."

Yang Sen suddenly sprayed the corners with luminol reagent, and the originally smooth tile surface glowed with a faint blue fluorescence. Those invisible bloodstains were like revived blood vessels, winding towards the kitchen. "Secondary transfer of bloodstains." He said with a hint of excitement, "The murderer went to the kitchen to clean the murder weapon after the crime, and there may be key evidence left on the edge of the sink."

Lu Chuan walked to the coffee table, where two red wine glasses with lipstick marks stood facing each other quietly. "The victim's defenseless posture shows that the murderer is an acquaintance." He pointed to one of the tilted wine glasses, "The direction of the wine splashing was to the left, which was consistent with the direction of the blood spraying on the wall, indicating that the murderer was standing on the right side of the victim when he stabbed him." "Look at this!" Yang Lin suddenly squatted down, and the ultraviolet light swept across the gap in the floor. In the faint reflection, half a bloody shoe print gradually appeared, and the jagged pattern on the edge was clearly visible, "A size 43 sports shoe, the sole has irregular wear, which should be caused by long-term intense exercise."

Yang Sen took out a magnifying glass and put it close to the shoe print: "The pressure is unevenly distributed, and the color of the forefoot is darker, which means that the murderer's force point is forward." He gestured with a running posture, "This person is likely good at sprinting, or has a habit of combat training."

Lu Chuan stood in the middle of the living room, closed his eyes and recreated the scene in his mind. When he opened his eyes again, he stretched out his hand to simulate the trajectory of the murder weapon, and his fingertips accurately touched the center of the blood stain on the wall: "The first knife stabbed into the abdomen, and the deceased instinctively raised his hand to block it, so there is a defensive injury on his left arm." He turned to the French window, "The murderer pushed the person to the window, and the second knife went straight into the heart."

Yang Lin pulled up the surveillance video, which showed a suspect wearing a baseball cap and carrying a travel bag walking out of the apartment building. "Pay attention to his stride length." He paused the video and marked the size on the screen, "75 centimeters, which is exactly the same as the stride length of the shoe prints at the scene."

Yang Sen suddenly pointed at the blood drops high on the wall: "These satellite-shaped splash points are the key." He picked up a small piece of coagulated blood scab with tweezers, "The moment the knife was drawn, the blood was thrown to the surroundings due to centrifugal force, forming radial blood drops. The elliptical angle of each blood drop points to the murderer's position."

Lu Chuan stared at the bloodstains on the wall and suddenly walked quickly to the entrance. Next to the body of the strangled golden retriever, he found something strange: "Look here, there is a bloodstain on the door frame, located 1.6 meters away." He stretched out his hand and gestured, "The deceased struggled after falling to the ground, and his knees scraped against the door frame. This height can prove the murderer's true height."

"The degree of blood drying also has its own mystery." Yang Sen put on gloves and gently scraped the blood stains on the floor. "The edges of the blood stains on the carpet are jagged, which means that the body was dragged at least ten minutes after the murder." He pulled up the timeline, "What was the murderer doing during this time?"

Lu Chuan's eyes swept across the entire scene and suddenly stopped at the gap in the sofa. "Light up!" As soon as he finished speaking, Yang Lin immediately shone the inspection light at the bottom of the sofa. In the dim light, a half-smoked bloody cigarette butt was lying quietly in the dust.

"A perfect closed loop." Yang Sen picked up the cigarette butt with tweezers, and the evidence bag made a slight sound when it rubbed against each other. "When the smoker leaned over, the ash fell on the carpet, and when he stood up, the corner of his clothes rubbed against blood. This is the related evidence we are looking for."

Lu Chuan and others found some clues at the crime scene, such as cigarette butts, and the deceased was about 1 meters tall, which means he should be an adult. Males have relatively strong bodies. (End of this chapter)