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

"First, conduct a comprehensive survey of the perimeter of the cordon area, then gradually advance towards the location of the body in the drainage ditch at the core of the scene. Every step must be documented with images and written annotations." Yang Sen nodded in response, picked up the video recording equipment, and began recording the entire process of the surrounding environment. Yang Lin, on the other hand, held a camera and took photos of the scene's location and overview from different angles.

The two first entered the "remote investigation zone" outside the cordon, which is the area more than 10 meters away from the core scene. They focused their investigation on the community's cement path, the area around the sycamore trees, and the passageway between buildings 2 and 3. "First, check the perimeter for any traces of the suspect entering or leaving the scene, such as footprints, tire tracks, or items left behind," Yang Lin said, shining an investigation light on the cement surface to carefully observe the marks. The cement path, due to years of use, had many scratches and wear, but was generally smooth, and no obvious fresh footprints or tire tracks were found.

At the junction of the back wall of Building 3 and the north edge of the drainage ditch, Yang Sen noticed something unusual: "Yang Lin, there are fresh footprints here!" Yang Lin immediately went over and crouched down to examine it closely. The ground in this area was soil, slightly soft due to recent rains, with two clear footprints on the surface. The edges of the footprints were neat, with no obvious drag marks. "Preliminary judgment is that they are shoe prints. Extract them." Yang Lin took out magnetic powder and a boar bristle brush, using black magnetic powder to gently brush the footprints. As the powder adhered, a complete shoe print gradually appeared: "Shoe size 41, type of shoe is a rubber rain boot, the tread pattern is horizontal stripes, the stripe spacing is about 0.8 cm, the wear is relatively light, presumably a new shoe or a shoe that has not been used much."

Yang Sen immediately took out his footprint plaster casting kit and used cardboard to create a protective ring around the footprint to prevent plaster from overflowing. He then mixed the plaster solution at a 1:1.5 ratio and slowly poured it into the footprint, ensuring the plaster filled every detail. "The plaster will take about 40 minutes to solidify. Mark this spot as 'Outer Perimeter Footprint Point 1' and continue surveying other areas," Yang Sen wrote the number on a marker and inserted it into the soil next to the footprint.

The two men explored the passageway between Building 2 and Building 3 along a cement path to the west. The passageway was about 2.5 meters wide and the ground was also made of cement. In the middle of the passageway, Yang Lin found a few scattered black fiber fragments on the ground: "Yang Sen, use the fiber extractor to extract them." Yang Sen took out the fiber extractor, gently pressed it onto the fiber fragments, and completely removed them, placing them in an evidence bag labeled "Outer Periphery Fiber Sample No. 1." "These fiber fragments are relatively fresh, with no obvious wear on the edges, and may be related to the case," Yang Lin said. He shone an investigation light around the area but found no other fibers or debris.

The investigation proceeded eastward to the community wall, which was approximately 2.2 meters high and constructed of red brick. Several climbing marks were visible on the surface, but most were old. Yang Lin used a fingerprint brush dipped in silver magnetic powder to scrub the wall surface, but no fresh fingerprints were found. Outside the wall was a narrow, unnamed alley, uncovered by surveillance cameras. Lu Chuan had already arranged for team members to conduct door-to-door searches of the alley.

After completing the initial investigation of the distant investigation area, the two entered the "medium-distance investigation area," which is 5-10 meters away from the core scene. They focused on investigating the edges of the drainage ditch, the area around the sycamore trees, and the windows and air conditioner units on the back wall of Building 3. "The core scene is the drainage ditch. The suspect is likely to be active near the ditch, so we should focus on checking for traces along the ditch," Yang Lin pointed to the southern edge of the drainage ditch, where there was a grassy, ​​earthen slope with a gradient of about 30 degrees.

Yang Sen shone his survey light on the slope and quickly discovered important traces: "There are several messy footprints here, as well as tire tracks!" The soil on the slope was soft, and in addition to the trampled and flattened weeds, there were three different types of shoe prints and a clear tire track. Yang Sen marked them one by one: "Footprints No. 1, No. 2, and No. 3 at the center, and tire track No. 1 at the center."

The three researchers first processed footprint number 1 in the middle distance. This footprint was from a sports shoe, size 43, with a grid-like tread pattern, each grid approximately 1 cm on each side. There were obvious wear gaps in the forefoot tread, suggesting the owner frequently wore these shoes on rough surfaces. Yang Lin developed the footprint with red magnetic powder, while Yang Sen extracted it using plaster. Footprint number 2 in the middle distance was from a leather shoe, size 42, with a dotted tread pattern. The pattern was clear, and wear was slight, suggesting it was from business leather shoes. Footprint number 3 in the middle distance shared characteristics with footprint number 1 on the outer perimeter; both were size 41 rubber rain boot prints, indicating the person wearing the rain boots had been near a ditch.

“Tire tracks are crucial; they were most likely left by the suspect’s vehicle transporting the body or arriving at the scene.” Yang Lin measured the width of the tire tracks with a tape measure: “The tires are 18 centimeters wide, with longitudinal serrated patterns and a spacing of about 1.2 centimeters. The preliminary judgment is that they are tire tracks from an electric tricycle or a small truck.” He used an electrostatic adsorption device to extract trace amounts of material from the surface of the tire tracks and placed them in a test tube labeled “Mid-distance No. 1 trace material sample.” He then used trace extraction tape to preliminarily fix and extract the tire tracks.

On the trunk of the sycamore tree, Yang Sen discovered a fresh friction mark: "There is a horizontal friction mark about 30 centimeters long and 5 centimeters wide, about 1.5 meters from the ground. The bark has peeled off, exposing the fresh wood layer." Yang Lin shone the friction mark with a multi-band light source and found no bloodstains or fiber residue, but speculated that it may have been caused by the friction between the body or the tools used to move the body and the tree trunk. The two men photographed the friction mark and extracted a small amount of the detached bark.

There are six windows on the back wall of Building 3, all of which are old-style sliding windows. Yang Lin checked the condition of each window one by one: "The windows are all closed and locked. There are no fresh climbing marks on the window sills and no fingerprints on the glass surface, ruling out the possibility that the suspect entered or left through the windows." The air conditioner outdoor unit is installed below the window. There is a layer of dust on the surface of the outdoor unit, but no obvious signs of contact.

The exploration of the mid-range exploration area lasted for 1 hour and 20 minutes, during which four footprint samples were collected, including the outermost footprint No. 1, one tire track, one fiber sample, one bark sample, and one trace material sample. 126 photographs were taken, and 28 minutes of video were recorded. At this point, the plaster model of the outermost footprint No. 1 had solidified. Yang Sen carefully removed it, wrapped it in plastic wrap, and placed it in the evidence box. The two rested briefly before preparing to enter the core exploration area.

The core investigation area, namely the drainage ditch and the location of the body, is the most important part of the entire investigation. Upon reaching the edge of the drainage ditch, the two investigators first conducted a static observation and record of the body. (End of Chapter)