The first experiment took place at 6:00 p.m. on October 9th, during the city's busiest traffic hour. Hou Dali set off from Dai Xiaofeng's home in the east of the city, driving towards the office in the west. Traffic congestion occurred while crossing Jiangzhou Second Bridge, and it wasn't until 7:30 p.m. that the car arrived at Dai Xiaofeng's office in the west. The return trip from the west office to the east home took 45 minutes.
The second experiment was conducted at 5:40 p.m. on October 10th. Hou Dali left the office in the west, crossed Jiangzhou Second Bridge, and reached the home in the east, taking about 40 minutes. He then stayed in his car outside Dai Xiaofeng's home for 20 minutes before driving back to the west office. This time, he encountered a traffic jam on the bridge, and the trip took one hour and sixteen minutes.
After these two experiments, Hou Dali was almost certain that Dai Xiaofeng did not have the time to commit the crime. The detectives in the Major Crimes Unit believed this conclusion was reliable.
The second thing Hou Dali did was analyze the crime scene.
Since the incident had occurred a year ago, Hou Dali had to rely on the existing evidence. This was dependent on and limited by the technical expertise of the Criminal Investigation Squad's forensic team, and it was uncertain whether anything could be uncovered.
By reviewing the 74 photographs, documents, diagrams, and experimental reports left in the case files, Hou Dali hand-drew a diagram of the crime scene, paying particular attention to depicting the large amounts of blood and blood splatter.
While drawing the blood and splatter, he worked meticulously, like an artist painting a fine brushwork piece, carefully placing each large blot of blood and each drop of spatter on the diagram he created. This technique was inspired by Professor Fei from the Criminal Investigation Department, who taught the use of fine brushwork to reconstruct crime scenes.
Complete photographs of crime scenes often contain various details, which can be hidden in plain sight. Drawing them using fine brushwork is an effective method of discovering these hidden details. Professor Fei had adopted this technique primarily because he himself had transitioned from a career in fine brushwork painting to becoming a criminal investigator before moving to the Criminal Investigation Department at the political and law university to teach.
Although Hou Dali wasn't a professional in fine brushwork, the method suited his personal style perfectly, so he embraced Professor Fei's technique and developed his own three-dimensional perspective drawings. While his teacher's fine brushwork was two-dimensional, Hou Dali's three-dimensional perspective drawings were more lifelike. The common goal was to reconstruct the crime scene as accurately as possible using their respective methods.
When Hou Dali meticulously depicted the bloodstains, he was incredibly patient, using a magnifying glass to carefully count the droplets. He identified 517 visible blood droplets, most of which were concentrated at the bottom of the stairs. The first step from the bottom had 303 blood droplets, with sporadic droplets on the steps above. There were also 87 blood droplets on the northern wall, with the remaining droplets scattered across the other steps.
After counting the blood droplets, Hou Dali began to sketch them. This was a painstaking task that required extraordinary spatial abilities to reconstruct the scene into a three-dimensional view.
While detailing the blood droplets, he noticed smudges of blood in the photographs, particularly on the walls where the distribution of blood was quite complex. The blood droplets varied in form—some were dripped, others splattered, some were smeared, and others wiped. There were also droplets that appeared to have been flung onto the surface, with most of the splattered blood classified as medium-velocity droplets.
Additionally, he found several bloodstains that were hollow. Hollow bloodstains indicated the presence of air in the droplets, which burst upon impact, creating a hollow shape.
Upon discovering the hollow bloodstains, Hou Dali paused to think. He then picked up the magnifying glass again and made a new observation: on one spot, a bloodstain had dried before a new one appeared on top of it.
On the ground, there was a footprint, with seven blood droplets trailing behind it.
Approximately half a meter from the ground on the doorframe, there was a partial bloody handprint.
Reconstructing all the blood droplets into a three-dimensional scene was an extremely tedious task, requiring time and mental effort. After four consecutive days of work, Hou Dali finally completed the three-dimensional crime scene diagram.
During the drawing process, he realized from the blood distribution and shapes that the victim did not die immediately after being injured. The victim had coughed up blood at the scene, attempted to get up, and even moved around. However, due to the severity of the injuries, the victim eventually collapsed again and died.
This indicated that the time of death was not necessarily the same as the time of the attack; the attack must have occurred earlier. The autopsy report stated that the time of death was around 7 p.m., but if the attack happened 20 to 40 minutes earlier, the time of the crime would have been between 6:20 and 6:40 p.m.
However, according to the testimonies from Dai Xiaofeng's colleagues, Dai Xiaofeng was still at the office at 6:20 p.m., making it impossible for him to have committed the crime.
Like the detectives who had worked on the case before him, Hou Dali found himself at an impasse.
Footsteps echoed, and Zhu Lin, dressed in his police uniform, appeared at the door. Noticing the case files and the sketchbook on the table, he asked, "Are you working on a case? Which one?"
"The Chen Lingfei case. The archive only had one page of material, so I pulled the full file to enter the basic details. I've found some clues in the bloodstains," Hou Dali replied, slightly taken aback, as this was the first time he had seen Zhu Lin in uniform, prompting him to take several extra glances.
Zhu Lin sat down and carefully examined the sketchbook for a while before commenting, "Is this a diagram of the crime scene? It's different from the usual ones."
"I reconstructed the scene in a three-dimensional view based on the case file materials," Hou Dali explained.
The Chen Lingfei case was the most recent unsolved homicide, and despite months of effort, the task force had made no breakthroughs and was forced to shelve the case temporarily. The realistic three-dimensional diagram brought Zhu Lin mentally back to that blood-soaked room, instantly dampening his previously light mood.
After hearing Hou Dali's analysis, Zhu Lin pondered, "Your findings are valuable. The task force had focused their investigation based on the assumption that the time of death was at 7 p.m. If the time of death was actually 40 minutes earlier, it changes a lot of things. Moreover, the fact that the killer left the scene without ensuring Chen Lingfei was dead reveals something about the killer's character. However, bloodstains alone are not entirely convincing; we'll need to perform a new autopsy."
Hou Dali asked, "Is the victim's body still preserved?"
Zhu Lin replied, "The body is still in storage. The freezing costs are high, and if the case remains unsolved, the body will eventually have to be cremated. The original autopsy was done by Tian Tian, so we should have her conduct the new one as well."
Hou Dali received a call from Tian Tian and went to the technical department.
Tian Tian, her face devoid of any smile, coldly said, "The new autopsy results are the same as before. I stand by my conclusions."
"Now the question is whether the time of the attack and the time of death differ, and whether that can be determined through the autopsy," Hou Dali said. Although he had studied forensic science in the Criminal Investigation Department, there was still a significant gap between his skills and those of a professional forensic pathologist. He knew that it was possible to determine this through the autopsy, but he couldn't do it himself.
Tian Tian replied, "That depends on the autopsy findings."
"Based on the bloodstains, the two time points don't match. Specifically…" Hou Dali began, intending to explain the doubts he had uncovered in the case files.
Tian Tian interrupted him, "You don't need to explain. I'll make my own judgment."
"When will the results be ready?" Hou Dali asked.
Tian Tian replied, "The results will be ready when they are ready."
Though Tian Tian's attitude was cold, her technical skills were exceptional. Two days later, she produced a new autopsy report. One key finding in the report was "early-stage acute ischemic necrosis of brain cells." Tian Tian explained, "Neuronal deterioration generally requires a period of blood circulation to occur; after death, the biochemical process stops. This means that the victim did not die immediately but continued to breathe for some time. Based on the state of the ischemic necrosis in the neurons, this process lasted about an hour."
The autopsy results closely matched the conclusions Hou Dali had drawn from analyzing the bloodstains. Upon receiving the report, Zhu Lin immediately reopened the case and specifically requested Hou Dali's involvement in the investigation.
During the case analysis meeting, as requested by Zhu Lin, Hou Dali hand-drew the three-dimensional diagram on the blackboard and outlined the discovery that Chen Lingfei did not die immediately.
"Bloodstain patterns can often be very useful in reconstructing a crime scene. In this case, there are different clusters of bloodstains, most of which are medium-velocity stains, including those from coughing, smears from hair, and so on. The bloodstains on the wall show smear marks from multiple directions, with some areas overlapping... From these bloodstains, we can infer that the victim moved around after being injured, indicating that the time of the attack and the time of death are not simply equal," Hou Dali explained.
As a newly hired police officer, Hou Dali faced a room full of experienced detectives from the Major Crimes Unit without showing any fear, presenting his findings truthfully.
Zhu Lin had previously considered the idea of having Hou Dali work on cold cases, but it had only been a vague notion, and he hadn't fully gauged Hou Dali's actual abilities. Listening to Hou Dali analyze the bloodstains, Zhu Lin's thoughts began to crystallize.
Gong Jianmin, the vice squad leader of the Criminal Investigation Squad and captain of the Major Crimes Unit, assigned the third team to re-investigate the Chen Lingfei case.
The Major Crimes Unit had 48 detectives, divided into eight investigation teams and a mobile unit. Each team had two partners, with two teams making up a group. Each group had a police car and two computers, with police equipment provided according to standard specifications.
The third team's leader, Li Ming, wore a pained expression. He was already handling a home invasion robbery case, and adding the reopened Chen Lingfei case would stretch his team thin.
Zhu Lin said, "Li Ming, you're an experienced detective; stop looking so grim. Cases come in waves—sometimes it's busy, sometimes it's slow. We can't control that. I know your team is short-handed, but tell me, which team isn't? Which team doesn't have cases? You tell me. The home invasion case is already making progress, so it should be relatively easier. Bring Hou Dali over to help with the Chen Lingfei case."
After the meeting, Li Ming called Hou Dali over and said, "You interned with the second squad, right? We just transferred Li Chao from the second squad to our team, so you'll be working with him on this case."
Hou Dali was delighted. "Master got transferred too? He was my mentor when I was interning with the second squad."
Li Ming replied, "The transfer order just came through. He'll report this afternoon. Since you two know each other well, that's great. You and Li Dazui will be in charge of investigating the Chen Lingfei case. Report any leads to me. If you need more manpower, let me know, and I'll coordinate it."
That afternoon, as Hou Dali was working on the Chen Lingfei case, Li Dazui came over and greeted him with a punch to the chest, saying, "You rich second-generation kid, hiding it from your master all this time."
Hou Dali smiled without responding.
"A box of tea from my apprentice—I can still accept that," Li Dazui continued. "I just got transferred here, and you're loaned from the second unit. Li Ming passing this case on to us suggests what? It suggests that Li Ming doesn't have much confidence in solving it. Even though the time of the crime has been pushed forward, all the other conditions remain unchanged. It's still a confusing mess."
Hou Dali was determined to crack the Chen Lingfei case. Compared to the Yang Fan case, the Chen Lingfei case had much more useful information. If he couldn't solve the Chen Lingfei case, there was no point even trying with the Yang Fan case.
"Master, let's go to Chen Lingfei's house and take a look."
"Why rush? I haven't even found a chair to sit on yet."
"Your chair and your seat aren't going anywhere. But the longer we delay, the harder it will be to solve the case."
"You've got a point."
Hou Dali headed downstairs and drove an off-road vehicle to the crime scene.
Since the incident, Dai Xiaofeng had not entered the new house, and the keys had been handed over to Chen Lingfei's mother.
When Hou Dali and Li Dazui arrived at the crime scene, Chen Lingfei's mother was already waiting at the door. She was an associate professor at Jiangzhou Normal University, with a scholarly demeanor, a serious expression, and a furrowed brow. She opened the door and said, "No one has entered since the crime. I always felt that you would need to come back to examine the scene. Thank you for remembering my daughter's case."
Hou Dali had brought luminol reagent and a UV lamp with him. At the corner of the stairs, he turned on the UV lamp and observed the luminol reaction, noting that the blood droplet shapes matched those recorded in the case file.
Meanwhile, Li Dazui chatted with Chen Lingfei's mother in the living room. As she talked, her eyes frequently shifted toward Hou Dali, who was carefully examining the scene. After half an hour, she couldn't help but ask, "What is this officer investigating? Has he found anything new?"
Li Dazui replied, "Solving a case is like conducting a scientific experiment—it requires repeated study."
Chen Lingfei's mother shook her head. "It's not the same. Experiments don't harm people. The murderer killed my daughter, and I want justice for her."
Hou Dali finally put away the UV lamp, then used a magnifying glass to examine the doors and windows before joining them in the living room.
"Have you found anything new?" Chen Lingfei's mother asked.
Hou Dali didn't answer directly. Instead, he asked, "Was there anything unusual about your daughter before she was killed? Any details that were out of the ordinary?"
Chen Lingfei's mother shook her head repeatedly and said, "The police who handled the case before asked this question. To be honest, I didn't notice anything unusual. My son-in-law, Dai Xiaofeng, was very busy at that time, often working overtime. My daughter was actively preparing to conceive. Everything seemed normal."
"Did your daughter have a habit of keeping a diary?" Hou Dali asked.
"She used to keep a diary when she was younger because I made her. I even checked it daily. But after she went to college, she stopped keeping a diary and let go of that good habit. Later, when she started using Weibo, she would often write short posts there. I've read every single one, and there was nothing out of the ordinary."
After leaving Chen Lingfei's home, Hou Dali and Li Dazui got into the car.
"The Major Crimes Unit is full of seasoned detectives who handle cases very professionally. For a new detective like you to correct the timeline of the crime based on bloodstains is quite impressive. Digging up more substantial evidence is not impossible, but it's very challenging," Li Dazui said. "The victim's mother has a strong personality, probably from being a teacher for so long. Generally speaking, strong mother, weak daughter. According to Chen Lingfei's classmates and colleagues, she was very gentle and sometimes even a bit naive."
"Master, let's go check the physical evidence."
"Rome wasn't built in a day. Take it step by step, and you'll be able to keep going."
"I'll treat you to a big meal tonight. Let's invite Captain Ding and the colleagues from the second unit as well."
"A big meal is fine, but it counts as an apology for hiding your identity from us."
When they returned to the Criminal Investigation Squad, the two of them went to the evidence room.
The physical evidence from the Chen Lingfei case was scattered on the table, each piece labeled with an identification number.
Among the evidence were fingerprints collected at the scene, a dozen strands of hair found on the floor, cups from the dining table, and so on. Having studied the case file numerous times and drawn a three-dimensional diagram of the crime scene, Hou Dali now saw the physical evidence on the table and used his unique spatial reconstruction ability to mentally place all the evidence back at the crime scene. He scrutinized every detail of the virtual crime scene over and over until something struck him. His gaze fell on an evidence bag on the table.
Snapping back to reality, he reached out, picked up the evidence bag with tweezers, and through the transparent bag, he could clearly see it was a shopping receipt. The item purchased was soy-braised duck.
The timestamp on the receipt was clear: 5:12 p.m.
In addition to collecting items related to the crime scene, the forensic team had also taken items from the dining table, including the bones of the soy-braised duck. Seeing this evidence, Hou Dali fell into deep thought.
"What are you spacing out for?" Li Dazui asked.
After asking twice, Hou Dali seemed to snap out of it and said, "The case file includes Dai Xiaofeng's call records. He made a call to Chen Lingfei at 4:25 p.m."
"Calling his wife? A phone record doesn't prove anything," Li Dazui replied.
Hou Dali remained pensive but didn't voice his thoughts, as they weren't fully formed yet.
That night, Hou Dali treated the entire second unit of Jiangyang District to dinner at Jiangzhou Hotel. During the gathering, everyone officially started calling Hou Dali by his nickname, "Pervert." The nickname spread so quickly through the Criminal Investigation Squad that even Hou Dali himself was surprised. Although a lot of alcohol was consumed at dinner, there were no additional festivities afterward. The detectives typically didn't spend much time at home, and it was normal for them to be away for several days or even weeks when on a case. So when they had the chance, they all tried to get home.
Hou Dali, being single, returned alone to Gaosen Villa, but decided to book a suite at the hotel instead. Shortly after entering the suite, the hotel's deputy manager, Gu Ying, arrived, pushing a large suitcase filled with Hou Dali's daily essentials, including a toothbrush, towel, and a change of clothes.
"Dali, we'll keep this room reserved for you from now on. Mei Jie is worried about you living here alone," said Gu Ying, who was in her thirties and well-maintained. She was a charming and resourceful character who wanted to persuade Hou Dali to move into the hotel permanently.
"I won't be coming often, so it would be a waste," Hou Dali replied.
Gu Ying joked, "You don't need to save money for the company. As Mei Jie's son, you should live a little more extravagantly. Let me explain what understated luxury with substance means. To have substance, one must be understated and, secondly, luxurious. If you're only understated without the luxury, then that's not really having substance."
"That's some twisted logic, Ying Jie," Hou Dali said with a smile. They all had their own nicknames—Gu Ying was Ying Jie, and she called Li Yongmei Mei Jie—so they didn't stand on ceremony with each other.
As they chatted, more hotel staff came in, bringing fresh fruit, milk, and desserts. Hou Dali was accustomed to this level of service, so he didn't think much of it.
Once everyone had left, Hou Dali opened his laptop and began searching through Chen Lingfei's Weibo posts.
Chen Lingfei had a regular posting schedule, almost always posting three times a day, and over time, her Weibo account had accumulated a significant amount of content. Her posts mainly focused on home decor, fashion, and travel, with a few posts about her daily thoughts. Unlike most girls, Chen Lingfei often posted landscape photos and rarely shared personal photos. Even when she did post personal photos, her face was never visible.
Recalling the expression on Chen Lingfei's mother's face, Hou Dali agreed with Li Dazui's assessment of the mother-daughter dynamic—strong mother, weak daughter. Chen Lingfei was gentle and demure, like a quiet flower blooming in a secluded valley. The thought of such a beautiful flower wilting just as it began to bloom filled him with sadness and anger in the dark of night.
There was a lot of content on Weibo, and Hou Dali read through it slowly. By early morning, he had only finished reading a third of the posts. As he lay in bed, images of the physical evidence flashed through his mind. When the duck bones appeared, he suddenly sat up.
The next morning, after leaving the hotel and entering the Criminal Investigation Squad building, the "prince" aura around Hou Dali faded away, and he immediately reverted to being a regular data clerk in the second unit. After cleaning the archive room, he received a call from Zhu Lin.
"Any progress on the Chen Lingfei case?" Zhu Lin asked.
"I visited the crime scene and reviewed the previously collected evidence. Objectively speaking, the forensic team's work was very meticulous, and their skills are excellent. However, the application of the evidence has been lacking; the dagger has been drawn, but it hasn't been thrust in," Hou Dali replied directly, without hiding his opinions. Criminal investigation is a science, and science does not tolerate any falsehoods. Hou Dali believed in speaking the truth, regardless of any non-scientific considerations.
Zhu Lin's expression became more serious. "So, you've actually made some progress?"
"It's not exactly progress, but I've discovered a lead that might be worth digging into," Hou Dali explained.
"Speak plainly, no need to keep us in suspense," Zhu Lin urged.
"There are some duck bones among the evidence, which could be a key breakthrough. The reason is simple: when people gnaw on duck bones, they often leave saliva behind, and saliva contains oral epithelial cells, which contain nuclear DNA. If we can extract saliva from the duck bones, we can compare it with potential suspects. Of course, it's possible we might extract the saliva and still not identify the suspect, but at least it would provide crucial evidence to narrow down our search. Once we have this evidence, it's only a matter of time before the suspect is caught."
Zhu Lin didn't immediately respond. He picked up the phone and called Gong Jianmin, the captain of the Major Crimes Unit, and Lao Tan, the head of the forensic department, to his office.
Lao Tan, who was in his fifties and balding, listened to Hou Dali's analysis, then said with wide eyes, "The duck bones were frozen, and our forensic lab doesn't have the capability to extract dried saliva."
Hou Dali replied, "The technical lab at the Criminal Investigation Headquarters can do it. I visited their lab while I was studying at the Criminal Investigation Department, and this was one of their key achievements."
Zhu Lin then turned to Lao Tan and asked, "Why did you decide to keep the duck bones in the first place?"
Lao Tan explained, "Xiao Lin was the one who conducted the crime scene investigation. He's a bit of a packrat and tends to collect a large amount of evidence every time. He probably didn't think through the significance of each piece of evidence at the time."
Jiangzhou had accumulated several unsolved homicide cases over the past few years, putting great pressure on the Criminal Investigation Squad. If the duck bones could serve as a breakthrough to solve the Chen Lingfei case, it would significantly alleviate the pressure on the squad. Zhu Lin immediately made the decision: "Lao Tan, make a trip to the headquarters. If they can't do it, ask them to request help from the Ministry of Public Security's Criminal Investigation Bureau."
While waiting for the test results, Hou Dali and Li Dazui continued their investigation, this time directly contacting Dai Xiaofeng.
Dai Xiaofeng's company, Fengling Technology, was located in the western part of the city. The "Feng" in Fengling was from Dai Xiaofeng's name, and the "Ling" was from Chen Lingfei's. The company was on the 18th floor of an office building, and Hou Dali and Li Dazui were led to Dai Xiaofeng's office. The office was about 100 square meters, with a large row of floor-to-ceiling windows offering a commanding view of the western city.
In Hou Dali's mind, he had imagined Dai Xiaofeng as a bespectacled, slightly frail techie. But in reality, Dai Xiaofeng did not wear glasses, and he was quite tall and well-built—not the weak scholarly type Hou Dali had envisioned.
After the secretary made tea and left the office, Dai Xiaofeng sat across from Li Dazui and Hou Dali and asked, "Officers, do you have new leads?"
Li Dazui replied, "We're handling the Chen Lingfei case and need to gather more information."
A look of disappointment appeared on Dai Xiaofeng's face. "Why is there another change in personnel? Every time you switch officers, I have to recount everything from the beginning. Does this mean you still don't have any solid leads?"
When dealing with a victim's family, Li Dazui's attitude was very serious. "The police have been pursuing this case continuously, and it's normal to adjust personnel from time to time. I just need to verify a few things."
As Dai Xiaofeng answered the questions, Hou Dali observed him closely, trying to detect any abnormal expressions. During the questioning, Dai Xiaofeng appeared to be deeply pained by the memories, often lowering his head, holding his face in his hands, and occasionally shedding tears.
After half an hour, the questioning ended. Dai Xiaofeng's statements matched the records from the Major Crimes Unit, and no new clues emerged. When Dai Xiaofeng lifted his head, his eyes were red, and his face was streaked with tears. He choked out, "I'm willing to cooperate with the police and am always ready to assist in the investigation. But I have one request: please don't keep changing officers. Every time someone new comes, I have to relive these memories, and it's incredibly painful."
As they left, Li Dazui asked, "What's your take on Dai Xiaofeng?"
Recalling his own feelings after Yang Fan's accident, Hou Dali replied, "The pain is real."
Li Dazui remarked, "You observed him for so long, and that's the only conclusion you came to?"
Hou Dali shrugged and said, "It's the only conclusion I can draw."
Li Dazui checked his watch and said, "Let's visit one more person—a colleague of Chen Lingfei's."
By early evening, Hou Dali and Li Dazui had finished their visit to Chen Lingfei's colleague, who lived not far from the Chen family. Li Dazui checked his watch again and said, "Let's grab some dinner. We've been walking around all day, and I'm starving. Tonight, you're treating me. Let's go to Binjiang Road for a drink."
Hou Dali replied, "No need for you to pay, Master. Don't be shy—Guolong Group's money comes from the people, so it should be spent on the people."
Li Dazui chuckled, "Having a rich second-generation apprentice is great—no guilt when eating and drinking."
The two of them went to the food court on Binjiang Road, a commercial area full of restaurants, and found the nicest small restaurant. They ordered grilled river fish and beer.
Hou Dali chose a seat facing away from the Jiangzhou River, avoiding looking at the water.
The Jiangzhou River is a seasonal river, and during the dry season, the water only reaches knee-high. Later, a tunnel was dug through Ma Bei Mountain outside the city, diverting water from Ma Xi River into the city, replenishing the Jiangzhou River. The increased water volume and faster flow made the river clearer, turning it into a popular spot for residents to linger in the evening.
As the river flowed by, a gentle breeze caressed their faces, and nearby diners engaged in lively conversations, creating a scene unique to the area. Li Dazui received a call from his wife, and he immediately stepped aside, holding the phone and nodding with a smile as he explained things to her.
When he returned to the table, Li Dazui explained his insistence on sitting by the river, "My wife and daughter are practicing music nearby. I suggested they come over here instead of me going home to cook."
Upon learning that Li Dazui's wife was coming, Hou Dali quickly ordered two more dishes. Of all the people in the Criminal Investigation Squad, Hou Dali was closest to Li Dazui, who never hid his fear of his wife, even in front of friends. Hou Dali had always been curious about this "River East Lion" and wondered just how fierce she really was. So when a petite, delicate-looking woman approached with an equally delicate little girl, he was surprised.