Not long after, Zhao Ming and the forensics team arrived at the scene.
"Sorry we're late, Captain Zeng," Zhao Ming scratched his head.
"What took you so long?"
"I was playing real-life CS (airsoft) with some friends. The place was kinda far from the city."
"Living quite the exciting life, huh?" Zeng Ping chuckled.
"I figured I'd practice my gun skills—might come in handy when catching bad guys," Zhao Ming grinned.
Zeng Ping didn't press further and turned to the forensics tech, Lu Wen, asking him to go collect fingerprints from the camera in the bathroom.
He then asked the victim, "Do you have any of your boyfriend's belongings here?"
"There's his cup under the desk," Chen Luyan pointed, starting to reach for it.
"Don't touch it. I'll get it," Han Bin said, putting on gloves and carefully taking the cup out.
"There are fingerprints," he said, handing it to the forensics team to collect samples.
"Captain Zeng, were there any prints on the envelope or the USB drive?"
"No clear ones," Zeng Ping replied.
A short while later, Lu Wen and another forensic officer completed the fingerprint collection and used a portable police fingerprint scanner to compare them on the spot.
This helped determine the investigation direction quickly and reduced the time needed to crack the case.
"Captain Zeng, the fingerprints on the camera don't match the ones on the cup," Lu Wen reported.
Zeng Ping nodded and handed the envelope and USB drive to Lu Wen. Even if there were no visible prints, latent ones might still be recovered with chemical agents or special equipment. Of course, if gloves were worn or the items were wiped clean, there'd be no prints at all.
"Officer, does that mean my boyfriend can be ruled out?" Chen Luyan asked, visibly relieved.
If her boyfriend had really done this, it would have terrified her even more.
Zeng Ping didn't respond directly. While the fingerprints didn't match, he couldn't rule out the possibility that the boyfriend had an accomplice. Since he had a key, he was still a suspect.
Just then, Li Hui returned from checking the surveillance footage.
"Find anything?"
"I spoke with the building management. There's surveillance at the front entrance, in the lobby, and in the elevators—but not in the stairwells, back entrance, or hallways."
"So, if the suspect knew the building layout or had checked it out beforehand, they could easily avoid all the cameras," Tian Li deduced.
"Yeah, commercial apartments usually only have a couple of towers, and the security is often pretty basic," Han Bin added.
"Anything suspicious from the cameras we do have?" Zeng Ping asked.
"No."
"I think we should have Miss Chen review the footage—she might recognize someone," Han Bin suggested.
Zeng Ping nodded. "This seems likely to be the work of someone she knows."
"I've copied the footage," Li Hui said, holding up a USB stick.
Chen Luyan used her computer to view the footage, while Han Bin and the others stepped aside to discuss the case quietly.
"Captain Zeng, the surveillance coverage has major gaps. Any suspect with half a brain would use the stairs. Not much point checking the cameras," Li Hui noted.
"I still think the boyfriend is suspicious. The lock wasn't forced. Without a key, no one could've installed that camera," Tian Li said.
"But didn't the fingerprints not match?" Zhao Ming countered.
"That doesn't mean much. Someone else might've touched the camera earlier—or they could be the prints of whoever sold it," Tian Li explained.
"In that case, this is getting more complicated," Li Hui sighed.
"Han Bin, what's your take?"
"I've examined the camera closely. I think the camera itself is a good angle to investigate."
"How so?"
"Well, if a camera was installed, it was obviously meant to record. That means the footage had to be either downloaded later or uploaded via the internet—that's how the blackmailer got the photos."
"Good point," Zeng Ping nodded. "If it was downloaded manually, the suspect would have to come back multiple times to retrieve the files. If uploaded online, the camera would need to connect to Wi-Fi."
"I checked earlier," Han Bin continued. "That camera uploads via Wi-Fi. The suspect can monitor everything in real-time using their phone or computer."
"The camera was hidden really well—surrounded by walls. A distant Wi-Fi signal wouldn't reach. That means the suspect used a nearby Wi-Fi network," Li Hui added.
Han Bin took out his phone and reviewed a photo of the camera he'd taken earlier. "342."
"What does that mean?"
"It's the network name the camera was connected to."
"You said 342?" Chen Luyan suddenly spoke up.
"You know it?"
"That's my Wi-Fi network! I use that to connect."
"Who else knows your Wi-Fi password?" Li Hui asked.
"Just me and my boyfriend."
"Did he help set up the internet too?"
"No, it was already set up by the landlord when I moved in," she said, suddenly remembering something. "Right! The landlord set the password too—so he definitely knows it."
"That means the landlord is also a suspect," Zeng Ping concluded.
"But the landlord doesn't have a key," Tian Li pointed out.
"That's an assumption," Han Bin said. "He may not have a key now, but he definitely did before she moved in. The camera could've been installed before she even rented the place."
"Exactly!" Tian Li realized. "Then we should compare the fingerprints from the camera to the landlord's."
Zeng Ping turned to Chen Luyan. "Have you ever cleaned your router?"
"It sits near the window and gathers dust, so I wipe it down often."
"Routers are usually installed by the internet provider, so the prints might not be helpful," Han Bin noted.
"Try to remember if the landlord left anything behind—or touched anything in the apartment," Tian Li asked.
Chen Luyan frowned, thinking for a moment, then shook her head. "It's been two months since I moved in. I deep-cleaned the place after moving. I can't recall anything specific."
"When you signed the rental contract, did you both leave fingerprints?" Han Bin asked.
"I remember now! I didn't want to do that, but the landlord insisted. He said it was safer if both parties left fingerprints."
"Show us the contract."
A few minutes later, she brought out the rental agreement. The fingerprints were left in red ink, so they didn't need to be collected—just compared.
Lu Wen compared them and confirmed,
"The fingerprint on the rental contract matches the partial print found on the hidden camera. This person is highly suspicious."
Although only a partial fingerprint had been recovered, the match was enough for Zeng Ping and Han Bin.
The odds of two different people having the same partial fingerprint in a single case were virtually zero.
(End of Chapter)