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

"Before entering the core scene, we first conducted a survey of the entire third floor to determine if there were any other related traces," Yang Lin said. The two slowly moved along the outer corridor of the third floor, turning on multi-band light sources and survey lights to conduct a comprehensive search of the floor, walls, and ceiling. About 5 meters from the frame of the room where the body was located, they found a set of blurry footprints on the corridor floor. In addition to the previously discovered size 42 striped rubber-soled shoe prints, there was a new set of footprints.

“These new footprints are from leather shoes, approximately size 41, with a diamond pattern. The edges of the footprints are clear, the stride is about 68 centimeters, and the stride angle is 12 degrees. They were also left by an adult male,” Yang Lin said after taking the measurements. “The direction of the footprints is towards the room where the body was located, which is consistent with the direction of the size 42 rubber-soled shoe prints, indicating that two adult males went to the core scene.” Yang Sen added, “The wear on these leather shoe prints is relatively light, indicating that the shoes are relatively new, which is inconsistent with the clothing habits of homeless people. They are most likely the footprints of the deceased.”

On the wall of the corridor, the two also found a wiping bloodstain, located 1.5 meters above the ground, about 30 centimeters long and 5 centimeters wide. The bloodstain was dark red. "The wiping direction of this bloodstain was from left to right, with irregular edges and obvious wiping marks. It was probably left by the suspect or the deceased wiping the wall with blood-stained hands or clothing during the move." Yang Lin used a fingerprint brush to scan the area around the bloodstain, but no complete fingerprint was found, only a few blurry fingerprint fragments.

At 10:10 AM, the two completed their survey of the outer perimeter of the third floor and began entering the core scene—the framework of a room on the north side of the third floor. The room framework was approximately 20 square meters in area, with an opening on the north side without windows. Sunlight streamed in through the opening, illuminating the interior. Scattered on the floor were discarded plastic sheets, cardboard boxes, and mineral water bottles. The body, wrapped in a pile of blue plastic sheets, was located in the center of the room.

"First, we'll take a panoramic shot of the core scene to capture its original state." Yang Sen operated the camera, starting from the entrance of the room and recording a panoramic view of the environment inside the room, the position of the body, and the surrounding items in a clockwise direction. He then used a digital camera to take still photos from different angles, including the overall position of the body, the state of the plastic sheeting, and the distribution of surrounding items. Yang Lin set up survey markers at the entrance of the room and used a laser rangefinder to measure the dimensions of the room and the distance between the body and the surrounding items: "The room is 5.2 meters long and 3.8 meters wide. The body is 2.5 meters from the north entrance and 1.8 meters from the room entrance, in a supine position."

After securing the body to its original state, the two began examining the traces around the body. About one meter east of the body, they found a bloodstained single-edged dagger. The dagger was approximately 25 centimeters long, with a 15-centimeter blade. The handle was made of black plastic and had a small amount of blood and fingerprints on its surface. "This dagger is most likely the murder weapon!" Yang Lin carefully used tweezers to hold the end of the dagger's handle, avoiding disturbing the fingerprints. "Yang Sen, first take photos of the dagger to preserve its shape, then extract fingerprint samples from the handle and blood samples from the blade."

Yang Sen used his camera to take close-up photos of the front, side, handle, and blade of the dagger, focusing on the distribution of bloodstains and areas with fingerprint residue. Yang Lin then used transparent fingerprint tape to extract fingerprints from the handle, finding a complete fingerprint with clear lines. He then used a cotton swab dipped in a small amount of saline solution to extract blood samples from the blade, placing them in an evidence bag labeled "Core Scene-001." "The dagger was located to the side of the body, relatively close, consistent with a frontal stab followed by disposal," Yang Lin analyzed.

Around the body, the two investigators found a large amount of blood, mainly concentrated beneath and within a 1.5-meter radius of the body, forming an irregular pool of blood about 1.2 square meters in area. The blood was dark red, and some areas had already congealed. "The pool of blood is relatively intact, with a small amount of splattered blood at the edge. The splatter direction is towards the left side of the body, indicating that the stabbing occurred while the body was lying supine, and the stabbing direction was from right to left," Yang Lin said, shining his investigation light on the edge of the pool of blood. "The droplets of splattered blood are about 1-3 millimeters in diameter, which is a medium-speed splatter, consistent with the characteristics of splatter caused by the heart pumping blood, indicating that the deceased still had vital signs at the time of the stabbing."

Yang Sen discovered several clear footprints around the pool of blood, including a size 42 striped rubber-soled shoe print and a size 41 diamond-patterned leather shoe print: "The rubber-soled shoe print has multiple overlapping marks around the pool of blood, indicating that the suspect lingered around the body after stabbing it; the leather shoe print is mainly concentrated under the body, matching the body's supine position, confirming it as the victim's footprints." The two men measured and photographed these footprints in detail, and extracted plaster models of some of the footprints.

In addition, about 0.8 meters west of the body, a men's wallet was found on the ground. The wallet was made of black leather, with a small amount of blood on the surface. The zipper was open, and the inside was empty. No ID card, bank cards, or other identification items were found. "The wallet was empty and showed signs of being rummaged through. We cannot rule out the possibility that the suspect murdered the victim for money." Yang Lin picked up the wallet and carefully examined its interior. "The bloodstains on the wallet are the same color as the bloodstains in the pool of blood, indicating that it is the victim's wallet, which fell off during the stabbing." After photographing the wallet to preserve its authenticity, Yang Sen extracted blood samples and fingerprints from the wallet's surface and placed them in an evidence bag labeled "Core Scene-002".

At 10:25 a.m., the two began examining the blue plastic sheet covering the body. The sheet consisted of three layers, all common industrial plastic, approximately 0.1 millimeters thick, with a small amount of dust and bloodstains on the surface. "First, we photographed the state of the plastic sheet covering the body, then slowly opened it layer by layer, carefully observing the marks on the plastic and the exposed parts of the body," Yang Lin said.

After Yang Sen photographed the overall state of the plastic sheeting, the two carefully peeled back the layers one by one. Upon removing the first layer, the victim's lower limbs were revealed; the victim was wearing black trousers and black leather shoes, the style of which perfectly matched the previously discovered size 41 diamond-patterned shoe print. Removing the second layer revealed the victim's torso, wearing a white shirt with a clear tear in the chest area, stained with copious amounts of blood. The tear was an irregular triangle with lacerations along its edges.

"The tear in the shirt is located on the left side of the chest, corresponding to the location of the heart. The size and shape of the tear roughly match the width of the dagger blade, indicating it was caused by a stab wound." Yang Lin measured the tear's dimensions: "The tear is approximately 6 centimeters long and 2 centimeters wide, consistent with the dagger blade's length of 15 centimeters and width of 2.5 centimeters." Yang Sen then photographed the bloodstains and fibers at the tear and extracted a small sample of shirt fibers. (End of Chapter)