Several leads were investigated simultaneously. In the end, the buyer's nearby neighbor was the first to yield results—the building had few residents, and only two households could hear what was going on in the buyer's home. One of them was away on a business trip. Before long, the police brought in the sofa buyer's only neighbor.
He was a middle-aged man with glasses. He walked slowly and spoke slowly, with a sluggish, lifeless air about him.
He shuffled downstairs behind a junior officer and looked around. "What happened?... Wh-why is someone lying here?"
Officer Takagi showed him the seriousness of the situation so he would cooperate properly. "There was a fresh corpse hidden inside the sofa your neighbor bought. Where were you between 2:00 and 3:00 this afternoon? Did you hear any unusual noises?"
The neighbor stared blankly at the sofa and the dead body for quite a while before finally processing the shocking fact. He thought for a moment. "Between 2:00 and 3:00 in the afternoon... I'm usually at home then, because I work at night and need to catch up on sleep during the day."
"But today..."
As though he had remembered something, he said uncertainly, "Now that you mention it, I did wake up earlier than usual today. Thinking carefully, I was probably woken up by the sound of an argument next door."
"An argument?" Officer Takagi's eyes lit up. "What exactly were they arguing about? Did either voice have any distinctive characteristics?"
The neighbor tried hard to recall, then shook his head. "I could only tell that they were two women. I couldn't make out anything more specific."
Officer Takagi scribbled furiously, carefully recording every suspicious detail.
After recounting everything he knew, the neighbor slowly made his way back upstairs.
In front of the building,