The crackdown on organized crime began with the arrest of the mother-in-law.

Chapter 921 On-site Investigation

"Director Qin, the unfamiliar fingerprint is a whorl pattern with a papillary line density of 14 lines/cm and sweat pore indentations on the edge. It is estimated that the user is male, between 25 and 40 years old, and right-handed." He handed the tablet to Qin Chuan, on which the search results of the national fingerprint database were compared. "No match in the criminal record database. It may be an innocent person, or it may be a premeditated crime where gloves were temporarily removed after the crime was committed."

Criminal Investigation Detachment Chief Li Ming squatted in the footprint investigation area, and the size 42 shoe print on the electrostatic adsorption film was projected onto the large screen: "The composition of the oil stain has been analyzed. It mainly contains mineral oil, graphite and ethylene glycol, which is consistent with the scenario of car repair and maintenance." He turned to look at the parking lot on the first basement floor of the building, "Xiao Chen, check all the vehicles with size 42 shoe prints that entered the parking lot today, especially the repair personnel."

“Team Leader Li,” Technician Xiao Chen held up the evidence bag, “the shoe print has irregular wear around the edges, with the pressure point concentrated on the forefoot, which suggests it’s from people who stand for long periods, such as security guards, cooks, or auto mechanics.” Her gaze swept over Zhao Yang, the parking lot security guard who was being questioned. He was rubbing his hands together, his cuffs stained with obvious machine oil.

Forensic pathologist Zhang Lin used tweezers to pick up the black wire from the victim's neck and rotated it in front of the investigation light: "There are five scratch marks on the surface of the wire, three of which show broken metal wires, consistent with the force pattern of friction against the railing." He pointed to the spiral twist marks at both ends of the wire, "Twisting marks by hand, the murderer has a strong grip with both hands, and may have a fitness habit or engaged in physical labor."

"Could it be a female murderer?" Qin Chuan suddenly asked, his gaze falling on the diamond earring in the evidence tray. "Zhang Lin, was the skin tissue on the earring tested beforehand?"

"The results just came out," Zhang Lin said, flipping through the rapid test report. "The ABO blood type is B, and the STR typing indicates female, aged 20-35. The tissue found under the deceased's fingernails is also from the same person, likely caused by scratching the assailant during the struggle."

Li Ming pulled out a copy of the deceased's communication records: "Guo Jianfeng dialed an unknown number at 2:07 PM. The base station location was within 500 meters of the Jinshan Building. The technical department tracked that the number made a call at a convenience store 10 minutes later. The convenience store's surveillance camera captured a blurry figure—wearing a red dress, sunglasses, and taking a can of Coke." He handed the surveillance screenshot to Qin Chuan. The moment the red dress swept past the shelf was captured. "The Coke can had a customized advertisement for Jinshi Financial on it, so it might be an internal staff member or a customer."

Xiao Wang from the investigation team ran over with a bag of evidence: "The 'Yuxi' cigarette butt at the corner of the fire escape staircase contained saliva. The DNA profile indicated male, ABO blood type O, which does not match the blood type of the deceased or the unfamiliar fingerprints. The cigarette butt filter had bite marks, and the dental arch was narrow, suggesting that the smoker was under 30 years old and right-handed."

“Zhao Yang has type B blood,” Li Ming frowned. “Who is this smoker with type O blood? The cigarette in Guo Jianfeng’s pocket is a Marlboro, which doesn’t match the brand of this cigarette butt, indicating that a third person was present at the time of the incident.”

Qin Chuan stared at the electronic lock at the rooftop entrance: "The employee ID card swipe records show that the access control was opened twice, at 13:05 and 15:17. The first time, Guo Jianfeng himself entered, and the second time, it continued until the time the case was reported. It is very likely that the murderer used the deceased's employee ID card to enter twice." He turned and pointed to the vomit next to the railing, "The security guard's vomit tested negative for occult blood, which was indeed caused by shock, ruling out the possibility of him being involved in the crime."

Zhang Lin opened his portable autopsy kit and used a probe to pry open the deceased's eyelids: "The subconjunctival hemorrhages are distributed in a tree-like pattern, consistent with mechanical asphyxiation. But..." He examined the deceased's mouth with a magnifying glass, "There is a small amount of white powder on the oral mucosa, which requires further toxicological testing. It may be a sedative drug."

“Sedatives?” Li Ming immediately thought of the parking ticket. “Guo Jianfeng entered the parking lot at 12:03 and went up to the rooftop at 13:05, leaving a gap of one hour. If someone drugged him in the car and then lured him up to the rooftop to kill him, that would explain the disparity in physical strength.”

“There’s something wrong with the Coke that the woman in the red dress had,” Qin Chuan nodded. “Investigate the batch of customized Coke that Jinshi Financial Company distributed today, as well as Guo Jianfeng’s dining situation.”

Technician Liu held up the wires as he walked towards the survey vehicle: "The outer sheath of the wires is printed with 'Akihabara 227IEC01 (RV) 450/750V 1mm?0?5', which is a common office wire. The building's property warehouse has the same model." He showed the collection record provided by the property management, "On the 28th of last month, Jinshi Financial Company collected two rolls for office relocation wiring."

"In other words, the murderer may be someone inside the building who is familiar with the environment and has access to the electrical wires," Li Ming noted in the investigation notebook. "Focus on investigating employees of Jinshi Financial Company, especially those who have received electrical wires."

At this moment, the technical department sent a new message: "Team Leader Qin, the unfamiliar fingerprint has been matched - it belongs to Zhang Wei, the chef of the restaurant on the third floor of the building, who was warned last month for stealing ingredients."

Qin Chuan immediately led his team downstairs, only to find Zhang Wei cooking in the restaurant's kitchen, his right hand wrapped in gauze. "How did you hurt your hand?" Li Ming lifted the gauze, revealing a fresh knife wound across his tiger's mouth.

"It was an accident while chopping vegetables," Zhang Wei said, pulling his hand back. "It has nothing to do with that dead man! I haven't even been to the rooftop today."

After comparing the fingerprints, Wang Qiang shook his head: "The patterns don't match. Zhang Wei has a whorl pattern, while the fingerprints at the scene were looped. We can rule that out."

Back on the rooftop, Xiao Chen was analyzing the overlapping footprints: "The footprints from the second person entering the rooftop covered part of the first footprints. Gait analysis shows that the second person walked slower and may have been carrying heavy objects." She pointed to the drag marks next to the fence, "The body's movement trajectory is obvious. The murderer adjusted the body's position after the murder, possibly to fabricate the scene."

Zhang Lin tidied up the autopsy instruments: "The preliminary autopsy is over. I suggest focusing on three points: First, the contents of the deceased's stomach to confirm whether there are any drug residues; second, the purchase channel of the earrings. The small diamonds are of ordinary material and may have come from a cheap jewelry store; third, compare the unfamiliar fingerprints and cigarette butt DNA with the city's database, especially those of people who recently joined the building."

As Qin Chuan gazed at the city skyline where countless lights gradually illuminated, he stuffed his investigation notebook into his trench coat: "Li Ming, tonight, investigate the female employees of Jinshi Financial Company, especially those wearing red dresses and with blood type B. Zhang Lin, expedite the toxicology test; I need to know if Guo Jianfeng lost his ability to resist before he died."

Li Ming nodded, the beam of his flashlight sweeping across the ventilation duct in the corner of the rooftop: "Also, there are 17 blind spots in the building's surveillance system. Focus on reviewing the footage from the freight elevator and fire escape. That figure in the red dress..." He paused, "may not be the first person to come into contact with the deceased, but she must be the last."

As the survey vehicle drove away, Wang Qiang was still spraying luminol reagent in the corner of the rooftop. In the instant the blue light flashed, half a bloody shoe print appeared behind the ventilation duct—it was the print of a size 42 work shoe, the oil stain gleaming with a faint blue light under the fluorescent light.