Chapter 41.1: Our Line of Work
Municipal Police Bureau, Forensic Sketch Room
“The last seven-year sample… up! That’s it—we’re done!”
Standing in front of the wall, Huang Xueling carefully clipped the image she had just finished drawing onto the cotton cord with a wooden clothespin.
Once it was secured, she happily clenched her fist and pumped it once in front of her chest. Then she hopped backward two steps and stood before the wall, admiring her handiwork with a satisfied smile.
The once-empty wall now had several horizontal lines of thick cotton cord strung across it.
Hundreds of completed diagrams of lock-cylinder marks had been clipped onto them one by one by Huang Xueling.
Arranged chronologically from left to right, the sheer number of diagrams covered more than half the wall.
At a glance, the uniformly sized illustrations looked like rows of soldiers standing at inspection—orderly and perfectly aligned.
“You finished that quickly?”
Hearing the noise, Jiang Xia stopped gazing into the distance from the hallway and returned her attention to the room. She turned and walked into the forensic sketch room, immediately seeing the entire wall covered in drawings.
It was just like looking at paintings in an art studio back in the day.
The students’ drawings back then had varied wildly in skill, so even from a distance, you could tell them apart. But with these diagrams, even from afar, those depicting the same angle looked practically identical.
Once she moved closer and compared them side by side, however, the wear marks left on the lock cylinders became extremely clear.
Jiang Xia walked from left to right, examining them as she went. She nodded in satisfaction.
“They really are much easier to see this way.”
“It’s all thanks to you for drawing them so well, Jiang Xia.”
Huang Xueling planted her hands on her hips, genuinely impressed by Jiang Xia’s persistence.
A few days ago, while Jiang Xia was taking a break after finishing some drawings, Huang Xueling had gotten curious and taken a couple of peeks through the microscope herself. The magnified details of the lock cylinders were an absolute mess. She couldn’t even tell one feature from another, and after staring for only a minute or two, she already felt dizzy.
Yet Jiang Xia could stare through it for several hours at a time, drawing as she observed, and had spent nearly two months doing it without ever getting tired of the work.
“If you hadn’t drawn the diagrams this large and in such detail, I wouldn’t have been able to make out anything at all.”
As she spoke, Huang Xueling walked over to Jiang Xia. Pointing excitedly at the pin-tumbler sections in several of the diagrams before them, she said:
“Looking at them side by side like this, even I can tell that these are the marks left by normal unlocking with the original key. When the lock was still new, the marks left behind were distinct lines. After being used many times, those lines were worn smooth. Even the tips of the pins became deformed, making them look as though they’d been slightly dented inward!”
“Hey, Xueling, you’re finished already? Why didn’t you call me?”
Trace Examiner Li pushed open the half-closed door and walked in. He glanced at the wall and immediately let out an impressed “Whoa.”
“Good grief, this is quite a sight!”
“I was just about to have Xueling call you over.”
Jiang Xia turned around and beckoned to Li. “Now that most of the drawings are finished, all that’s left is to compare their shape characteristics. Come take a look too.”
“That’s exactly what I came here to talk about.”
Li took two steps forward and stood in front of the drawings.
These diagrams hadn’t been completed in a single day. He had already gone over the actual marks again and again before this, so he was quite familiar with the traces shown in them.
“Looking at the diagrams, the marks left by the original key are mainly found on the surfaces of the pin heads, the cylindrical surfaces of the lock pins, and their outer ends. In particular, around the pin holes in the lock cylinder, there are streak-like scratches everywhere.”
As he spoke, a hint of excitement entered Li’s voice.
“As for a duplicate key, because it’s a new key, its edges are relatively sharp, so it’s also more likely to leave marks. Especially on locks that have been used for a longer period and whose surfaces have been worn smooth—the traces are even clearer, and they’re basically quite similar to those left by the original key.”
“Of course, that depends on the precision of the duplicate. Take this one, for example. The key was poorly duplicated, so there’s more play when it engages with the lock, leaving quite a few scraping marks around the grooves.”
“But regardless of the circumstances, we can now confirm one thing: we can definitely distinguish between the lock marks left by an original key and those left by a duplicate key!”
Jiang Xia nodded as she listened.
After Li finished speaking, Jiang Xia said, “As a summary, there’s no problem with it. It’s enough to solve that particular case, but it still isn’t sufficient to establish a definitive standard. We have to start with the locations of the marks and explain why traces are left in those particular places, what characteristics those traces have, and sort out their shape, size, texture, and so on. Only then can we use them as a standard for identification and verify the results again.”
“The characteristics of the marks are easy enough. Basically, we just have to look at what they resemble and summarize the patterns.”
Hearing this, Li said, “But the locations of the marks definitely involve things like force, right? I can’t figure that part out. That’ll have to be you.”
“No problem.”
Jiang Xia nodded. “All that’s left is to put everything together. This is the final leg of a long journey. Once we finish writing it, we can submit it for publication.”
At that, Li immediately perked up.
Jiang Xia had done most of the work on the research herself. He hadn’t contributed much, so naturally, he wasn’t shameless enough to insist on putting his own name down as an author. But the department had provided quite a bit of logistical support, and Jiang Xia would ultimately add ‘All Members of the Technical Division, Criminal Investigation Division, Changning Municipal Public Security Bureau’ after her own name, along with a word of thanks to the leadership.
With the entire department listed, if you rounded things up, he could still say he’d been published in a journal.
How impressive would that sound when he told people about it!
“Good, good, good. I’ll summarize all these marks as quickly as I can.”
After agreeing, Li suddenly remembered what had prompted them to do all this in the first place.
“By the way, Jiang Xia, we’ve pretty much finished examining these lock-cylinder marks. When are you planning to look into that burglary-and-infant-murder case?”
“After we finish the paper and submit it.”
Jiang Xia had already made up her mind.
“The case happened so long ago that there’s a very good chance the relevant evidence has already been destroyed. All that’s left is the lock marks, but that aspect is still a blank in the field of forensic science. Once we arrest the suspect and finish the interrogation, all we’ll have is their confession and the lock marks. Those two pieces of evidence alone won’t carry much weight with the court. There’s a good chance the case will be sent back because the evidence is insufficient.”
“Why don’t we submit the paper first? ‘Criminalistics and Forensic Science’ is a bimonthly journal. If everything goes quickly, it might even make it to the court around the same time. Having a published paper to back it up would give the evidence much more weight.”
It was a good idea. Trace Examiner Li nodded in agreement.
“Then let’s get to work. Let’s try to submit it as soon as possible.”
“Mm.”
Jiang Xia returned to her desk.
Her desk was now covered with books.
She had never written a research paper for publication before and had absolutely no idea how to begin. Fortunately, Photographer Zhao happened to have three issues of ‘Criminalistics and Forensic Science’ that she could use as references. She had borrowed them and flipped through them countless times.
But Jiang Xia still felt that wasn’t enough. She wanted to make the paper detailed enough to withstand scrutiny, so she went to the library and borrowed several books on mechanics to study.
As for the results…
They were pretty effective at putting her to sleep.
After all, no matter how good she’d been at physics in her previous life, she had only been at an ordinary level. She wasn’t some naturally gifted physics competition student. Trying to teach herself advanced mechanics was simply impossible for her to understand, so of course it made her sleepy.
But that didn’t matter.
Jiang Xia had a cheat.
‘Deep Blue, give me a boost!’
She casually added the experience points she’d earned from picking locks that day to physics and mechanics.
In an instant, quite a bit of additional knowledge about mechanics appeared in Jiang Xia’s mind.
She read through the books while working through several problems involving deformation and applied forces, practicing until she had become familiar with the concepts. Only then did she turn back and begin writing the paper.
She agonized over every word. After two hours, she’d managed to write only 1,300 characters, and her head was already throbbing.
Once she was tired of writing, Jiang Xia put down her pen and went outside to get some fresh air.
Two familiar faces from the Third Squad, Bai Fangqiang and his mentor Tian Jianguo, came up the stairs one after the other.
Seeing Jiang Xia outside, Bai Fangqiang waved in greeting.
“Morning, Jiang Xia. Getting ready to go eat?”
Jiang Xia glanced up at the sun. It really was already approaching the middle of the sky.
It was indeed about time to head to the cafeteria for lunch.
“Pretty much.”
While pondering the monumental question of what to eat for lunch, Jiang Xia casually asked, “You two just finished up?”
“Yeah. We just finished taking a statement.”
Bai Fangqiang said, “We ran into a pretty unusual case today. Last night, when the accountant at the Supply and Marketing Cooperative was counting the money, she discovered six counterfeit cloth coupons. She reported it, so they called us over. When I saw them, I thought, wow—the counterfeits were made so well that they were practically identical to the real ones! No wonder they managed to fool the ticket clerk.”
Counterfeit coupons?
And they were practically indistinguishable from the real ones?
What colleague had such incredible craftsmanship? She had to go take a look!
Jiang Xia had originally been about to head downstairs for lunch, but she stopped in her tracks, turned around, and followed Bai Fangqiang toward the Third Squad’s office.
“Counterfeit coupons that look exactly like the real ones? I have to see these.”
“Go ahead.”
Bai Fangqiang didn’t think much of it, assuming Jiang Xia was simply curious.
“They’re in the office.”
As they spoke, they had already reached the Third Squad’s office. Tian Jianguo pushed open the door, and the scene inside immediately came into view.
Several members of the Third Squad were gathered together. At the center, Squad Leader Feng Zhengming was holding two cloth coupons of the same denomination up to the light, examining them carefully.
“It’s identical. Way too identical. This counterfeit is exactly the same as the real one. There’s simply no way to tell them apart!”
The other officers nodded in agreement.
“Exactly. It just looks a little more worn, but otherwise it’s completely genuine.”
“This person made it so convincingly.”
“And where exactly are those serrated edges the cashier mentioned? I’ve been looking forever and can’t find them…”
…
…
They really were that convincing?
Hearing everyone’s comments, Jiang Xia became even more curious. She quickly walked into the office, gently nudged one of the Third Squad members aside, and stood beside Feng Zhengming’s desk. She carefully examined the two cloth coupons in his hands.
The cloth coupons were three cun long, light purple throughout. A symmetrical ring of intricate, dark-purple security patterns was printed across the top. In the center were the three characters “壹市尺”, meaning “one market chi”, with an official seal stamped beside them.
The seal read: “Issued by the Changning Municipal Government.”
One of the two cloth coupons was brand-new, while the other was crumpled, its color slightly duller. It looked as though someone had accidentally squeezed it and then left it sitting around for a while, making it look a little old. At first glance, it seemed like nothing more than the difference between something new and something aged by time. There was absolutely no way to tell which was genuine and which was counterfeit.
But this little trick was nowhere near enough to fool Jiang Xia.
“Whoever made this has a pretty good knack for aging things.”
She raised an eyebrow.
“But the counterfeit itself is still a little off. The color isn’t quite right.”
“Huh?”
Hearing her, Feng Zhengming turned around. When he saw who it was, a hint of surprise appeared in his eyes.
“Jiang Xia? Aren’t you examining those lock marks? What brings you to our office?”
“Bai Fangqiang said you guys had caught someone making counterfeit coupons, and that they were practically identical to the real ones. I got curious and came over to have a look.”
Jiang Xia said casually, “It’s not every day you see something like this.”