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

Xiao Lin asked. Zhang Kai nodded: "The brick fragments need to be compared with the fragments extracted from the bag during the on-site investigation. The fiber samples need to be compared with the fibers of the canvas bag and the coarse fibers found under the willow tree to see if they come from the same source. This could very well be traces left by the deceased during a struggle with the suspect or when he was dragged. It can also help determine whether the location where the body was dumped is the primary crime scene."

To confirm the cause of death and obtain more details, Zhang Kai began an autopsy. He used a scalpel to cut along the midline of the abdomen, separating the skin, subcutaneous tissue, and muscle in sequence. Putrefactive gases mixed with the stench of the canal water rushed out instantly, and Xiao Lin quickly adjusted the exhaust system to minimize the odor. "There was a large amount of pale yellow liquid in the abdominal cavity, about 600 ml, which was initially determined to be a mixture of ascites and canal water," Zhang Kai said, using a suction device to remove the liquid. "The liver and spleen were in a semi-liquefied state, soft in texture, and crumbled easily when touched with tweezers, consistent with the putrefaction changes of tissues 5-7 days after death; the contents of the intestines had been mostly emptied, with only a small amount of brownish pasty material remaining. No undigested food residue was found, indicating that the deceased had eaten 8-12 hours before death. Based on the time of death, the last meal was estimated to have been between 6 pm and 8 pm four days ago."

During the thoracic dissection, Zhang Kai was even more cautious. As the sternum was sawed open, the internal condition of the thoracic cavity gradually became clear—the upper lobe of the left lung was obviously collapsed, the lung tissue was dark red, and a large amount of foamy liquid could be seen flowing out after the incision was made. These were typical characteristics of drowning death, but Zhang Kai frowned: "No, although there are signs of drowning, the weight of the lung tissue is lighter than that of a normal drowned body, and the amount of silt in the alveolar cavity is very small. It is more like a small amount of canal water inhaled when the body was thrown into the canal after death, rather than suffocation caused by voluntary drowning."

He further examined the neck tissue and found obvious bleeding marks in the sternocleidomastoid muscle and infrahyoid muscle group, a fracture of the greater horn of the hyoid bone, and only a small amount of mucus in the trachea and bronchi, with no obvious silt or algae—which perfectly matched the previous conclusion of "strangulation." "The cause of death has been determined to be mechanical asphyxiation, caused by strangulation with a strip of material," Zhang Kai said, using tweezers to pick up the damaged muscle tissue in the neck and showing it to Xiao Lin. "The degree of bleeding in the neck muscles and the fracture of the hyoid bone prove that the strangulation force was sufficient to cause death by respiratory failure; as for the drowning-like appearance in the lung tissue, it was formed when the body was thrown into the canal after death, and the canal water passively entered the respiratory tract. It is a post-mortem phenomenon and not a true drowning death."

Xiao Lin suddenly realized: "So, the deceased was strangled first and then thrown into the drainage ditch? Does that provide evidence for our previous speculation that the body 'stayed on land for a period of time after death'?" Zhang Kai nodded: "That's right. Judging from the vital signs of the neck injury, such as bleeding and muscle contraction, the strangulation occurred before death; and the slight drowning characteristics in the lung tissue indicate that the body stayed in the ditch for 1-2 days less than the time of death. In other words, the deceased was thrown into the ditch 1-2 days after death. This also explains why the decomposition process is slightly different from that of a body in water alone—decomposition begins in the early stages under normal temperature conditions on land, and the speed slows down after entering the water."

During the autopsy, Zhang Kai discovered a crucial detail. Embedded in the skin tissue of the victim's left wrist was a small metal fragment with obvious grinding marks on its edges, initially identified as brass. "This fragment looks different from the wrench fragment found at the scene, but its shape resembles a part of some tool," Zhang Kai carefully removed the fragment with tweezers and placed it in a specimen bottle. "It will be sent for analysis of its composition and morphology to see if it came from a screwdriver, pliers, or other repair tool—this could be an item the victim carried with them, torn off during the struggle with the suspect, and embedded in the skin. It could also provide clues to confirm the victim's identity or occupation."

As the autopsy neared its end, Zhang Kai summarized all the findings, going through each item on the record board: "The deceased was male, 40-50 years old, 178cm tall, died between 0:00 and 3:00 AM 5-7 days ago, caused by mechanical asphyxiation, strangled by a cotton or hemp strip; suffered blunt force trauma such as bricks or wooden sticks, resulting in damage to the right temporal region and injuries from fighting, with abrasions on the right palm, nail fragments, and fibers; was dumped into a drainage ditch 1-2 days after death, possibly having been in a normal-temperature environment on land before being dumped; a brass metal fragment was embedded in the left wrist, possibly from a repair tool; the last meal was between 6:00 and 8:00 PM 4 days ago, with no drug residue found in the stomach, ruling out poisoning; no identification documents or jewelry were found on the body, and the clothing was mostly decomposed, with only a small amount of fiber remaining, requiring DNA comparison or a missing persons database to confirm the identity."

"Could the wrench fragments and cigarette butts found at the scene all point to the same suspect? Could the dark red stains on the metal hook be the victim's blood?" Xiao Lin asked, sorting through the autopsy report. Zhang Kai took the report and added notes at key points: "If the oil on the wrench fragments matches the machine oil found at construction sites, it can further confirm the suspect's connection to the construction industry; if DNA can be extracted from the cigarette butts, it can be compared with skin tissue fragments found under the victim's fingernails to confirm whether they belong to the same person; if the metal fragments can be identified as coming from a specific repair tool, it can also suggest that the victim's occupation may be related to mechanical repair or construction, providing direction for the identity investigation."

He paused, then continued, "Furthermore, if the brick fragments under the victim's fingernails are consistent with the bricks found at the demolition site upstream of the drainage ditch, combined with the band-like pressure marks on the neck, the crime process can be further reconstructed—the suspect may have had an argument with the victim at or near the demolition site, struck the victim's head with a brick causing him to lose consciousness, then strangled him with a band-like object, and then wrapped the body in a canvas bag and transported it to the drainage ditch to dispose of the body. During the process, he accidentally dropped wrench fragments and cigarette butts, and the bag was torn by a tree branch, leaving behind fibers and fragments."

As the body was resealed and sent to the cold storage, Zhang Kai removed his gas mask, his forehead already drenched in sweat. He looked at the autopsy report and the specimen bottles filled with various samples on the table; every piece of data had been repeatedly checked, and every conclusion had clear pathological evidence. "Send these samples to the technical department immediately. Prioritize testing for metal fragments, fiber materials, cigarette butt DNA, brick debris, and fibers from the neck indentation," Zhang Kai instructed Xiao Lin. "Also, simultaneously provide Team Leader Lu with key information such as the time of death, cause of death, and time of body disposal, so they can adjust their investigation direction, focusing on 'construction industry personnel active 5-7 days ago in the early morning' and 'missing persons aged 40-50 working in maintenance or construction.'" (End of Chapter)