Xu Mo extended his hand towards the officers, and everyone noticed the layer of dust on his palm.
The lights in the stairwell were old and dim, so the officers hadn't initially noticed the dust on the door of apartment 202, nor had they thought that this unit had been unoccupied for a long time.
However, after the woman's reminder and Xu Mo's validation, the officers began to notice this detail.
They had already checked the first and second floors, finding no suspicious points.
Next, the group continued up to the third floor.
The situation at apartment 301 was similar to that of 202, with a layer of dust on the door. However, the dust on the door of 301 was thicker, suggesting it had been unoccupied for at least a year or two.
Then came apartment 302. The shoe rack outside 302 had a few pairs of women's shoes and a single pair of men's shoes with hardly any signs of wear.
"I don't think we need to check this unit, right?" Wang Dachuan quickly chimed in. "This one's probably a single woman living alone. I read online that some women do this for safety reasons, putting men's shoes outside to make it seem like there's a man in the house."
Before he could finish, Chen Ke gave Wang Dachuan's shoulder a firm pat.
"Not bad, kid. You're improving!"
Compared to Wang Dachuan, Chen Ke was more experienced, having been at the station longer and serving as Wang Dachuan's senior. He had basically watched Wang Dachuan grow from a naive rookie into what he was now.
Since the occupant of 302 was a single woman, the officers decided against knocking on the door and instead went straight to the fourth floor, as their suspect was male.
One of the units on the fourth floor wasn't asleep yet. The poor soundproofing of the old building allowed the officers to hear noises from inside as they were halfway up the stairs.
It sounded like a quarrel.
After knocking on the door, a woman in her fifties or sixties opened it slightly, her eyes red, clearly having just cried.
"Hello, we are officers..." Han Fei said while showing his badge.
Before he could finish, the woman opened the door wide and stepped aside, inviting them in.
The inside was a mess, with shattered plates, bowls, glasses, and even the television in the living room having been thrown.
From the second bedroom came the sounds of scolding and dissuasion.
"I'm sorry to bother you so late, officers," the woman said, wiping the tears from her eyes and clearing some of the debris with her feet to make space for Han Fei and the others.
She then shouted toward the bedroom, "Stop it! The police are here!"
Han Fei was initially puzzled, but quickly understood.
This family was having a serious argument, which was why the woman had opened the door as soon as she heard the officers. She likely thought they were there to mediate their family dispute after receiving a report.
At that moment, a middle-aged man holding a "Septwolves" belt emerged from the second bedroom, followed by a young couple.
The sounds of scolding earlier must have come from the father disciplining his child, while the couple's voices were likely their attempts to stop him.
After a quick scan of the room, Han Fei determined that the suspect's video wasn't taken in this apartment.
Though the investigation was important, the family's conflict seemed severe. The man's belt was even broken, likely from hitting the child too hard. Han Fei decided to stay and mediate.
With Xu Mo's abilities, Han Fei trusted he could handle the rest of the investigation.
"Xu Mo, take them upstairs. I'll stay here. This family seems serious; I'm afraid something might happen," Han Fei whispered to Xu Mo, glancing at the man's belt.
"Should I leave a couple of people with you?"
"No need. I can handle this myself. They can help you."
Xu Mo turned to leave to check apartment 402, but stopped after taking a few steps and returned.
He looked at the couple who had just come out of the second bedroom, the ones who had tried to stop the man from hitting the child.
The couple was wearing pajamas and slippers. Based on this, Xu Mo deduced they lived in 402, likely having come over to intervene after hearing the commotion from 401.
"Are you the ones living in 402 across the hall?"
"Yes," they both nodded.
Xu Mo's hunch was right. He continued, "Could you please open your door? We're chasing a suspect, and we believe he may be hiding in this building."
"Oh? We thought you were here to mediate the argument," the couple said, surprised but cooperative. They left 401, unlocked 402, and opened the door.
Xu Mo glanced inside and confirmed that the video hadn't been taken there. After a brief explanation, he left, taking the officers up to the next floor.
Han Fei stayed behind in 401 to mediate the family's dispute.
The fifth and sixth floors were quickly checked, and none of the four units showed any signs of the suspect. The interior layouts didn't match the video's footage.
"That's strange..." Chen Ke scratched his head. "Could the suspect not be in this building?"
They had checked from the first to the sixth floor without finding the suspect. Chen Ke even began to wonder if Xu Mo had made a mistake, and the suspect wasn't in the building at all.
Xu Mo also furrowed his brow. Based on his investigation, the suspect's IP address used to upload the video was from this building—he was confident he hadn't made a mistake.
There must be something they missed...
What could it be? Xu Mo recalled everything they had seen since entering the building.
101 and 102 were occupied by elderly couples. He had deduced this from the shoes on the shoe racks. Since the elderly usually go to bed early, Xu Mo hadn't disturbed them.
201 had no suspicions; they had checked inside. 202 was unoccupied and couldn't possibly be involved.
301 was also unoccupied, while 302 housed a smart single woman.
None of the six units on 401, 402, 501, 502, 601, and 602 had connections to the suspect, as each had been checked and their interiors didn't match the video's footage.
Units 202 on the second floor, 301 on the third, and all units from the fourth, fifth, and sixth floors showed no suspicions.
That left the two elderly couples on the first floor and the single woman in 302.
"I think I know..." Suddenly, Xu Mo had a flash of insight. "Let's go downstairs!"