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

When Wang Shuai's police car pulled up at the back door of the yoga studio, morning mist was seeping through the gaps in the sycamore leaves, dampening the steps. He held Lin Weiwei's yoga class attendance sheet in his hand; the signature at 8:05 PM on May 12th matched her daily records perfectly. The angle of the pen tip and the slant of the horizontal strokes matched 98% in the handwriting analysis system. "Check the changing room surveillance footage again," he told Officer Li beside him. The footage showed Lin Weiwei entering the hot yoga room in size 37 sneakers at 8:10 PM and not leaving until 10:03 PM. The wear marks on the heels perfectly matched the marks on the yoga mat—ironclad proof that she had never left.

The yoga studio's registration book had a note from the instructor on duty stating, "Lin Weiwei took an energy bar due to low blood sugar between 19:45 PM and 19:50 PM," slightly contradicting her claim that she "didn't leave the room the entire time." When Wang Shuai found the instructor, she was demonstrating Downward-Facing Dog to a student, her yoga pants still covered in grass clippings: "I was watching her when she took the energy bar; I stood at the front desk for five minutes and didn't leave the main entrance." The energy bar's packaging was found in the trash can; the DNA on it matched Lin Weiwei perfectly, and the timestamp on the packaging showed an opening time of 19:46 PM, further narrowing down the time gap.

"Zhang Lijun is his cousin?" Wang Shuai's fingers traced across the note Lin Weiwei provided. "A surgeon at the First Municipal Hospital?" Lin Weiwei was massaging the student's shoulders and neck with essential oil, her avocado green nails drawing an arc on the student's back. "His cousin. Last year, he borrowed 100,000 yuan from Zhang Lihui, saying it was for his wife's medical treatment, and he still hasn't paid it back." She suddenly stopped, the essential oil bottle spinning in her palm. "Zhang Lihui has been urging him several times. Last month, I even went to the hospital to confront him, and the two of them almost came to blows arguing in the corridor."

When Wang Shuai retrieved Zhang Lijun's identity information, the photo on the screen stunned him—a 41-year-old man wearing a white coat, his eyes behind gold-rimmed glasses gleaming coldly, and a noticeable scar on the second joint of his right ring finger. "Deputy Director of Neurosurgery at the First Municipal Hospital," Xiao Li flipped through his resume, "specializing in craniocerebral surgery. Last year, he was suspended for three months due to a medical malpractice incident, reportedly paying a considerable amount in compensation to patients—this might be why he borrowed money." More importantly, his height was 174cm, and he wore size 42 shoes, perfectly matching the characteristics deduced from the footprints at the scene.

When Wang Shuai found Zhang Lijun, he was performing a craniotomy in the operating room, his scalpel moving steadily under the microscope. Wang Shuai waited in the corridor for three hours. When the surgery was over, Zhang Lijun took off his mask, the cuffs of his white coat smelling faintly of iodine. "Did you need something?" His voice was weary from the surgery, his gold-rimmed glasses slipped down to the tip of his nose, revealing the bloodshot eyes—like the fresh wear and tear on the edge of the size 42 shoe print at the scene, revealing an undisguised anxiety.

"Where were you from 8 PM to midnight on May 12th?" Wang Shuai's notebook lay open on the nurses' station counter, the pen tip hovering over the words "Zhang Lijun, male, 41 years old, neurosurgeon." The man's Adam's apple bobbed as he reached for his cell phone in his white coat pocket: "I was on night shift at the hospital. The department's shift schedule can prove it, and there are also medical records..." Before he could finish, Wang Shuai interrupted him: "We checked the shift schedule; you were off on May 12th."

Zhang Lijun's fingers suddenly clenched, the metal tube of the stethoscope leaving red marks on his palm: "Oh... I remembered wrong, I was at home with my wife that day." His gaze drifted to the window at the end of the corridor, "I played chess with the neighbor around 9 pm, you can go ask him." Wang Shuai immediately asked Xiao Li to verify, but the neighbor, Grandpa Zhao's testimony was contradictory: "He did play chess, but he left at 9 pm, saying there was an emergency at the hospital—this doesn't match the statement that he was 'at home with his wife'."

Even more suspicious was Zhang Lijun's vehicle information. He owned a black Volkswagen sedan, and checkpoint surveillance footage from 9:15 PM on May 12th showed the vehicle on the county road leading to Wild Wolf Valley, with its front facing the same direction as the valley. "I'm going to the countryside to visit an old relative," Zhang Lijun's explanation sounded flawless, but when Wang Shuai pulled up the inventory list, he found an entrenching tool in the trunk. The soil composition on the shovel head was exactly the same as the soil in the valley, and there were even traces of pine fiber remaining.

As a neurosurgeon, Zhang Lijun had easy access to cyanide. Hospital pharmacy records show he applied for 50ml of potassium cyanide on May 10th, stating the purpose as "experimental research," but there was no record of it in the laboratory's usage log. "That bottle of potassium cyanide is still in the safe," his voice suddenly changed, "Go check if you don't believe me." But pharmacy surveillance footage showed that when he received the medication, he packaged it separately in a black plastic bag, a storage method completely different from ordinary laboratory supplies.

While investigating the debt dispute between Zhang Lijun and Zhang Lihui, Wang Shuai discovered an anomaly in the bank statements. Zhang Lihui's account received a transfer of 5 yuan on May 11th, with the remitter listed as Zhang Lijun's wife, but the note read "repayment"—contradicting the claim of "borrowing 5 yuan and not repaying it." "He's only willing to repay half first," Lin Weiwei said over the phone. "Zhang Lihui was so angry he smashed a glass and said he'd sue him at the hospital for embezzling public funds—part of the money for Zhang Lijun's wife's surgery was supposedly from the department's research funds."

Zhang Lijun's shoe size became a key breakthrough. The forensic team took samples of his size 42 leather shoes left in the hospital changing room. The tread pattern on the sole perfectly matched the rubber sole imprints found at the scene at 16 characteristic points, especially the triangular wear area on the outer forefoot, which was identical to the pressure marks found in the muddy mountain hollow. "This wear was caused by prolonged standing during surgery," the trace evidence expert wrote in the report. "The pressure on the right forefoot was 12% greater than that on the left foot, consistent with the gait characteristics of a right-handed doctor."

When Wang Shuai produced a photo of the farm tricycle, Zhang Lijun's face turned deathly pale. The tricycle, parked at the hospital's back gate, had cyanide residue detected on the inner wall of the metal drum in its cargo bed, a substance identical to that found in the ashes from the mountain hollow. "This is my father-in-law's tricycle," he said, fiddling with the buttons on his white coat, "I borrowed it on May 12th to haul fertilizer..." He was interrupted by Xiao Li before he could finish: "We checked your father-in-law's farmland; they used organic fertilizer in May, so they didn't need chemical fertilizer at all."

The most damning evidence came from Zhang Lijun's scalpel. In his office drawer, technicians found trace amounts of leather fibers on the handle of a scalpel numbered "037," perfectly matching the composition of the LV leather found under Zhang Lihui's fingernails. "When this scalpel was sent for sterilization last week, the usage record was 'none,'" the head nurse's testimony was like a hammer blow, "but the blood pretreatment residue on the scalpel matched Zhang Lihui's blood type." (End of Chapter)