After waiting for a while and seeing that no one spoke up, Jiang Ling began to give a hint.
“From a psychological perspective, a criminal needs to be familiar with the crime scene but also fears being recognized by acquaintances. Therefore, they tend to choose relatively convenient locations to commit their crimes.”
Jiang Ling’s words were easy to understand, and Li Zhenliang and the others all nodded in agreement.
“I get what you mean. It’s like rabbits don’t eat grass near their burrows—thieves usually don’t strike near their own homes.”
“But if it’s too far, the thief won’t dare to go. After all, they’re unfamiliar and afraid something might go wrong.”
“Not too far, not too close… this…”
Jiang Ling gave another hint: “In that case, we can take the suspect’s residence as the center of a circle and the farthest reachable distance as the radius, forming a psychological boundary.”
Upon hearing this, Liu Haoran immediately stood up, grabbed a pencil from the table, and drew a circle on the map. Except for one crime scene that was too far away to be included, the other eleven crime locations all fit within the circle.
“This circle is the criminal’s psychological boundary?”
Jiang Ling nodded approvingly, took out a triangle ruler to measure the circle’s diameter, glanced at the scale in the lower right corner of the map, did a quick mental calculation, and said, “Right.
The diameter of this psychological map is about 500 meters. From my experience, the diameter of the circle containing serial crime locations usually ranges from 500 to 1000 meters.”
Sure enough, the power of the masses was infinite.
The circle Liu Haoran drew perfectly matched the “Circle Center Hypothesis” proposed by psychologists in country M: most criminals commit crimes around their residence, forming a “psychological safety boundary.”
Beside the crime scene not included in the circle was the number “7,” representing the seventh crime location.
Zhou Wei pointed at this lone crime scene, “Why isn’t this one inside the psychological boundary?”
Li Zhenliang and Liu Haoran exchanged a glance, and a thought suddenly popped into both their minds. They simultaneously reached out to grab the seventh report file.
Liu Haoran stood in front of the blackboard, farther from Jiang Ling’s desk, but Li Zhenliang beat him to it and took the report file, pulling out several photos of physical evidence.
“Look, the scratch marks on this bike handle are deeper and heavier than the others. It’s different from the other eleven cases and probably caused by a different tool.”
Liu Haoran pulled out photos of the bike handles from the other cases and placed them all side by side for comparison.
Zhou Wei’s eyes widened, and he slapped his thigh. “It really is! The scratches on this one are different from the rest.”
Jiang Ling hummed in agreement. “We can separate this case out. Since the physical evidence marks differ, the perpetrator is probably not the same person.”
Liu Haoran quickly set aside the seventh case, and the remaining eleven cases were combined for investigation.
Li Zhenliang sighed, “If Officer Ying were here, the forensic team could definitely determine what kind of tool caused the scratches.”
Zhou Wei shook his head. “This case is too small; it’s not worth bothering the forensic team. They’re swamped every day and probably don’t have time to help us.”
Zhou Wei’s words deflated Li Zhenliang’s spirits. It made sense—such a small case couldn’t possibly call in experts from the forensic team.
But Jiang Ling thought the suggestion was excellent.
She was good at criminal profiling but helpless when it came to physical evidence. If they could get a forensic expert to join the investigation of these eleven linked cases, it would definitely help solve the case.
With this in mind, Jiang Ling didn’t hesitate and picked up the red phone on Wei Changfeng’s desk.
Might as well ask and see if they could get a specialist.
The call connected, and a deep voice came through: “Hello.” It was Ying Songmao.
Jiang Ling got straight to the point: “There’s a series of cases involving eleven stolen bicycle bells. We’d like your help to examine the physical evidence photos.”
There was a moment of silence on Ying Songmao’s end.
Zhou Wei tensed up, clenching his fists tightly, holding his breath as he listened intently. Could the forensic team really help with such a minor case?
“Sure, send the photos by fax. I’ll take a look first.”
Hearing Ying Songmao agree, Zhou Wei’s tightly clenched fist suddenly shot up in the air, punching the void. This was fantastic! With the forensic team’s support, there was hope to crack the case.
“Thank you,” Jiang Ling said, giving Liu Haoran a look. He immediately gave a thumbs-up, grabbed the coded photos, and headed toward the director’s office.
Ying Songmao politely replied, “You’re welcome.”
He didn’t hang up right away, so Jiang Ling added, “Although this series of cases isn’t big, there are eleven of them. We’re currently discussing how to use spatiotemporal analysis to track the suspect’s living trajectory…”
Before she could finish, Ying Songmao interrupted quickly, “I’m on my way.”
Then the call ended.
Jiang Ling held the still-beeping phone, feeling very pleased.
In her previous life, she had never met Ying Songmao in person, but judging from his forensic reports and signatures, he seemed like a dedicated and straightforward person.
Someone like him would definitely be interested in new methods in forensic technology.
Playing to his interests really worked wonders.
Jiang Ling hung up the phone: “Officer Ying said he’ll come join our discussion.”
Li Zhenliang immediately brightened up and winked at Zhou Wei. “You said Officer Ying wouldn’t come. Looks like you were wrong.”
Zhou Wei wasn’t unwilling to ask Officer Ying; he just doubted he could get him.
Hearing Li Zhenliang’s words, Zhou Wei nodded repeatedly. “Yeah, yeah, it’s my mistake. Officer Ying is the city bureau’s top expert in forensic identification. It’s great that he can come.”
The two shared a smile, then suddenly both slapped their foreheads.
“Oh, hurry and call Haoran back. No need to fax the photos!”
Li Zhenliang and Zhou Wei rushed out of the office, shouting down the corridor, “Haoran, come back! Come back!”
Their loud voices startled all the officers in nearby offices, who came out to see what was going on.
Even Director Yao came out carrying his large tea cup. “What’s all the fuss about? Stop the commotion.”
Before he finished, Liu Haoran dashed out of the director’s office. “What’s wrong? Has Officer Ying backed out?”
Zhou Wei’s excited voice echoed in the corridor: “Officer Ying said he’s coming right away!”
Li Zhenliang couldn’t hide his pride. “Exactly! Haoran, hurry back! No need to fax the photos anymore. Officer Ying will see them in person.”
At that, Wei Changfeng ran up from the duty hall. “Officer Ying is coming? What’s he coming for?”
After hearing Li Zhenliang’s explanation, Wei Changfeng slapped his thigh. “I knew that Jiang Ling had guts. You all should learn more from her. See? One call and technical support from the city bureau is on its way. You focus on the case, I’ll wait downstairs for Officer Ying.”
Outside the case team’s office was bustling, but inside it fell silent.
Jiang Ling began pondering about Ying Songmao.
He was formally trained, only 26 years old, yet already deputy captain of the city bureau’s forensic technical team. His forensic skills were outstanding.
Logically, he should have stayed fully dedicated, so why hadn’t she seen any reports or signatures from him after 2000?
Was he transferred to another province?
Or changed careers?
Or…
Thinking of the last possibility, Jiang Ling’s heart jolted, and she quickly pushed the thought aside.
When Liu Haoran returned, the group continued their discussion.
Jiang Ling said, “Not too far, not too close, no repeats—that’s the suspect’s ‘three no’s’ principle. If we go by this idea, can we figure out where the suspect might live?”
“This jurisdiction is so big. How do we determine that residence?” Liu Haoran, who had just rushed back from the director’s office, was still a bit confused.
Zhou Wei stared at the map for a long time and said uncertainly, “If the thief won’t steal right outside their home, then we can exclude the area around the crime scenes.”
Jiang Ling nodded firmly. “Right. Continue.”
Encouraged, Zhou Wei continued observing the map, trying to enlarge the red circles around each crime scene.
When the eleven enlarged circles filled the screen, everyone’s mouths dropped open.
It looked like blooming red flowers, densely scattered across the Jinwu Road Police Station’s jurisdiction.
Only the center of the flowers left a blank space.
Zhou Wei was excited as if he had discovered a new continent. Pointing at the empty space in the middle of the red flowers, he shouted, “Look! This empty space perfectly fits your three no’s principle.”
Everyone’s eyes fixed on the blank area in the center of the red flowers.
Li Zhenliang excitedly stood up, nearly overturning his chair. “The Peony Towel Factory! That’s the Peony Towel Factory!”
The others chimed in, “Right, right, that’s the towel factory.”
Zhou Wei had been at the police station for a long time and often rode his bike around, so he was very familiar with the jurisdiction’s geography.
He pointed to the empty spot and said, “Peony Towel used to be a flagship brand in our city. Their products were good quality and cheap, and shopping malls nationwide fought to stock them. But in recent years, the factory’s staff became complacent, quality control slipped, and profits dropped. I heard it’s going to be restructured. They have nearly a thousand employees, three main workshops, two boiler houses, a big warehouse, an administrative building, a canteen, and a factory daycare center.”
A thousand people? Not as big as the Textile Factory, but still quite large.
Jiang Ling asked, “What about the dormitory area?”
Zhou Wei seemed to have a mental map of the jurisdiction and answered precisely, “Four dormitory buildings for ordinary workers, one building for management and engineers, and a row of old bungalows housing temporary workers and single employees.”
Liu Haoran slapped his thigh. “If towel factory workers commit crimes during their commute, the timing fits perfectly with the crime times.”
But Li Zhenliang stood up and pointed at the location marked “1” — the first crime scene. “Look, the first crime happened near the Textile Factory, which is farthest from the towel factory. Why would a towel factory employee go all the way there to steal bicycle bells? That doesn’t make much sense to me.”
Jiang Ling also felt it was odd. According to the “comfort principle,” a criminal usually commits their first crime close to home.
But this suspect was different, the first crime location was the farthest from the center. Why?
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