novelaction Chapter 1022 Bloodstain Analysis
Chapter 1022 Bloodstain Analysis
"Also, Yang and Sun, let's analyze the bloodstains carefully."
A tense atmosphere, like something out of a crime drama, enveloped the crime scene. Li Ming's tactical flashlight pierced the darkness, casting a cold white light on the bloodstains splattered on the wall. Xiao Sun knelt on the floor, the blue light of the multispectral imager flickering on his face, while Xiao Yang held a laser rangefinder, the beeping of the measurement data mingling with the sound of rain outside the window.
“Look at these medium-speed bloodstains.” Xiao Sun circled several fan-shaped bloodstains on the wall with a red marker. “The splatter angle is between 15 and 20 degrees. According to Locard’s principle of mass exchange, this shape indicates that the murder weapon pierced an artery when it was swung horizontally at a speed of 6-8 meters per second.” He suddenly switched the ultraviolet light to the 365-nanometer band, and dozens of tiny blood droplets immediately appeared at the base of the wall. “These satellite-shaped splatters were formed when the main bloodstains were ruptured due to surface tension. The victim should have been in an upright position when the murderer committed the crime.”
Li Ming crouched down, his flashlight beam tracing a line across the ground: "The dragging bloodstains on the floor have distinct layers. The upper layer is liquid and flowing, while the lower layer has accumulated blood scabs, indicating that the deceased was dragged for about 5 meters after being injured." He picked up a blood scab mixed with hair with tweezers. "The hair follicles are intact, which should be caused by the friction between the scalp and the ground during the dragging process."
Xiao Yang synchronized the data from the 3D scanner to his tablet: "Based on the parabolic trajectory model of the bloodstain's landing point, the starting height of the weapon's swing was about 1.9 meters, and the ending height was 1.2 meters. Combined with the splash speed, we calculated—" He pushed up his goggles, "The murderer's height is most likely between 182 and 188 centimeters, and the strength of his right arm is concentrated, indicating that he is right-handed."
Suddenly, Xiao Sun raised his portable spectrometer: "Captain Li, sodium chlorate was detected in the bloodstains on the wall, with a content of 0.3%." He pulled up the component analysis spectrum, "This is the main component of bleach. The murderer cleaned the scene, but the luminol reaction shows that there is still fluorescence residue under the original bloodstains." He pointed to a seemingly clean area in the corner of the wall, "The fluorescence intensity here is 37% weaker than other places, indicating that it was wiped clean in a focused manner."
Li Ming used his fingers to measure the folds at the edge of the pool of blood: "The cracks that appeared when the blood congealed pointed towards the entrance, indicating that the blood flow was disturbed by external forces." He turned to look at Xiao Sun, "Check the community's surveillance footage to see if anyone carrying a large container entered or exited during the time of the incident. The murderer may have diluted the blood with bottled water."
“Note these transferred bloodstains.” Xiao Yang used an electrostatic adsorption device to collect fibers from the side of the sofa. “The wiping direction is from the upper left to the lower right, which matches the movement trajectory of the right hand holding the object. Moreover, there are repeated smearing marks on the fabric, indicating that the murderer wiped it at least three times.” He put the sample into an evidence bag. “I suggest performing scanning electron microscopy analysis on the fibers, which may extract metal fragments from the surface of the murder weapon.”
Xiao Sun suddenly lay down on the floor, and a bright light illuminated the gaps in the tiles: "A trace amount of brain tissue has been found!" He carefully collected it with a biological tissue sampler. "It is grayish-white and mixed with blood, which should have been splashed when the skull fractured. Based on the degree of oxidation of the brain tissue, the fatal injury should have occurred in the final stage."
Li Ming drew a bloodstain distribution diagram on the whiteboard: "Now let's reconstruct the attack process. The murderer launched a surprise attack from the entrance hall. The first blow pierced the carotid artery with a sharp end, causing type A bloodstains." He pointed to a large fan-shaped bloodstain on the wall, "When the victim staggered backward, the murderer used a flat end to strike a second time, forming type B radial bloodstains."
“C-shaped bloodstains were created during the dragging process,” Xiao Yang added, marking it on the diagram. “After the victim fell to the ground, the murderer made at least two overhead slams, and the high-speed bloodstains on the ceiling and the pool of blood on the ground are evidence of this.” He brought up a 3D model, where the red bloodstains were dynamically simulated in the virtual space. “Look at this, the splash height during the third attack reached 2.5 meters, and the murderer must have been in a state of extreme excitement at that time.”
Xiao Sun held up the evidence bag containing hair: "These hairs have follicles at the roots, so we'll immediately conduct mitochondrial DNA testing. And—" He pointed to the bathroom, "the luminol reaction at the drain indicates there was a large amount of blood from cleaning there, so we recommend extracting biological samples from the inside of the pipes."
Li Ming stared at the crisscrossing bloodstains on the wall: "The murderer made two fatal mistakes when cleaning up the scene. First, he underestimated the sensitivity of luminol, and second, he created directional traces when wiping the bloodstains." He turned to the two men, "Enter all the bloodstain data into the bloodstain morphology analysis system, focusing on comparing it with armed assault cases that have occurred in the city in the past five years, especially those using steel pipes as weapons."
The rain intensified, and the three men's voices rose and fell amidst the bloody scene. Every calculation of the angle of the splatter, every analysis of the pattern of the bloodstains, was transforming the abstract crime into a concrete chain of evidence. And those silent bloodstains, through the interpretation of forensic experts, were gradually piecing together the violent trajectory of the murderer.
Two hours later, the on-site investigation was completed.
The body was transported back to the Criminal Investigation Division for autopsy.
The cold lights in the dissection room gleamed on the stainless steel workbench, and the pungent smell of formaldehyde mingled with the stench of blood filled the air. Zhang Lin, wearing a medical mask and goggles, clattered his rubber gloves against the metal instruments. His assistant, Xiao Chen, stood by, preparing a notebook and a video camera, nervously watching the dissection work that was about to begin.
“Let’s begin.” Zhang Lin’s voice sounded somewhat muffled through his mask. He first conducted a general examination of the deceased Li Baocun’s body. The deceased had multiple bruises on his face and a torn corner of his mouth, indicating that he had been violently beaten before birth. “The deceased is male, approximately 45 years old, with multiple blunt force injuries and scratches visible on his body.” As Zhang Lin spoke, he used a measuring tape to measure the length and location of the wounds, which Xiao Chen quickly noted down in his notebook.
Next, Zhang Lin picked up the scalpel and made the first incision along the deceased's chest and abdomen. The moment the blade sliced through the skin, a strong smell of blood filled the air. "Check the chest cavity first." Zhang Lin skillfully separated the pectoralis major muscle, cut the ribs with rib shears, and after opening the chest cavity, he carefully examined the condition of the lungs and heart. "Both lungs are dark red with obvious congestion, and there are a few bleeding points on the surface of the heart." He used forceps to pick up some lung tissue. "These symptoms indicate that the deceased may have suffocated, but the specific cause still needs further analysis."
During the examination of the stomach, Zhang Lin carefully removed it and placed it on the dissection tray. "The deceased's stomach contents were about 200 milliliters, mainly undigested rice, vegetables, and meat. Judging from the form of the food, it should have been consumed at dinner."