The example was well given, but please don't give it again next time.

"Go on, tell me." Han Fei was intrigued and urged Xu Mo to continue.

At this point in the investigation, the case could almost be classified as a "cold case."

Especially since this "cold case" dated back twenty years, it was even more of a headache.

Han Fei was even considering whether to give up on the case for now, archive it, and revisit it when they had more resources in the future.

Situations like this were quite common in the police system. Almost every local police station had one or two cases that officers couldn't solve, not because they were lazy, but because these cases were simply too difficult to crack. No matter how much manpower or resources were thrown at them, it often felt like a waste of time.

The key was that stubbornly pursuing such cases wasn't productive. It was smarter to temporarily shelve them and wait for better tools or insights in the future.

Of course, deep down, everyone knew that "when we have more resources" was just empty talk.

How hard were "cold cases" to solve? The officers knew all too well.

What exactly was a "cold case"? It was a case with absolutely no leads. Without any clues, what was there to investigate?

Even after ten or twenty years, such cases remained unsolvable. If the police had found even a shred of useful evidence, they wouldn't have chosen to archive the case in the first place.

Xu Mo took a moment to organize his thoughts and then looked at Han Fei.

"Captain Han, let me ask you something. Why do you think the killer hid the victim's body inside the bridge pier?"

"Isn't it obvious? To avoid being discovered. That spot was the safest, less likely to be found than burying it in the ground."

Xu Mo didn't respond immediately, just kept staring at Han Fei.

Under Xu Mo's gaze, Han Fei quickly realized something was off.

"Wait, the body was eventually discovered by us... And if the killer really wanted to dispose of the body completely, there were plenty of other methods. Why go through the trouble of stuffing it into a bridge pier? That method has a very low 'cost-effectiveness'!"

With his extensive experience handling multiple cases, Han Fei immediately spotted a puzzling detail.

Hiding a body inside a concrete and steel bridge pier was almost the riskiest way to dispose of a corpse.

Construction sites were always bustling with workers. If the killer had stuffed the body into the pier, there was a high chance of being spotted by the workers. If that happened, he'd be done for.

If the killer's primary goal was to keep the body hidden, he could have chosen far more secure methods.

Han Fei could instantly think of several ways to make a body "disappear" completely. While these methods were challenging, they were still far less risky than sneaking a body into a bridge pier under the noses of construction workers.

"Exactly," Xu Mo nodded. "In other words, the killer didn't hide the body in the pier to keep it from being discovered—at least, that wasn't his main goal."

"Then what was his main goal?" Han Fei asked.

Following Xu Mo's line of thought, Han Fei suddenly felt like there might be another way to crack this case.

In fact, he felt he was close to uncovering the truth.

"Good question!" Xu Mo raised his voice slightly.

His confident expression made Han Fei believe that Xu Mo was about to reveal the truth of the case.

For a moment, Han Fei couldn't help but look at Xu Mo with anticipation, his eyes practically saying, "Go on, keep talking!"

But the next second, Xu Mo shook his head. "Actually, I can't say for sure."

Han Fei: "???"

You can't say for sure, yet you just acted so confident? Wasting my time!

"But I have some theories," Xu Mo shifted the conversation. "In criminal psychology, there's a theory that some perpetrators return to the crime scene to seek a sense of accomplishment, to get a thrill, and to satisfy their twisted desires."

"I know that, but what does it have to do with the killer hiding the body in the bridge pier?" Han Fei couldn't quite connect the dots.

What was the connection between the two?

"There is a connection. Normally, if a body is left in a public area, the killer can only return once because the police will quickly remove the body. So, the killer only gets one chance to relive the thrill. But by hiding the body in the bridge pier, the killer can return frequently, indulging in that thrill over and over."

"That makes sense," Han Fei frowned. "But if that's the case, why not just bury the body in a remote area? The killer could still visit whenever he wanted, right?"

Xu Mo waved his hand dismissively.

"It's not the same. A remote area is deserted, but the Binjiang Bridge is bustling with people and traffic. That makes it far more thrilling and satisfying for the killer's twisted desires."

"Also, when a killer returns to the crime scene, it's because the scene is active—there are police and onlookers. That's what gives him the thrill. Burying the body in a remote area wouldn't have the same effect. But hiding it in the Binjiang Bridge's pier is different. Thousands of people cross the bridge every day, but no one knows there's a body inside the pier, and no one knows he's the killer."

"Let me give you an example. If Old Wang has an affair with a widow, he wouldn't feel much thrill. But if Old Wang had affairs with every married woman in his entire apartment building, and none of their husbands knew, wouldn't he feel a rush every time he walked through the building and saw these clueless men?"

That was a great example, but please don't use it again... Han Fei gave Xu Mo a strange look but didn't say anything. Instead, he furrowed his brow and thought for a while.

After a moment, he nodded.

"I see what you're getting at... So you think the killer must frequently return to the Binjiang Bridge, just to seek that thrill and satisfy his twisted desires."

"Exactly," Xu Mo nodded.

After a pause, he added another theory.

"There's another possibility. The killer harbored intense hatred for the victim, so he hid the body under the Binjiang Bridge's concrete pier. That way, he could stomp on the victim whenever he wanted, and even if he didn't have time, the countless people crossing the bridge would do it for him."

Han Fei nodded slightly. "So, you're saying the killer is likely to show up on the bridge, and we should stake out the area to look for suspicious individuals?"

"Yes, that's what I mean. We shouldn't waste any time. I suggest we head out now." Xu Mo glanced at the clock on the wall.

It was almost time. If they left the station now, they could reach the Binjiang Bridge by 6:10 PM.

That would leave them just twenty minutes before the system's clue pointed to 6:30 PM.