Confusion

"Ah geez, I should have just killed him, why am I such and idiot?" The killer said, as he fell onto the couch in a rundown apartment that he called home. The detective attempted to follow him, but failed. He looked at his watch and realized that he could go home for the day, plus he had a day off the next day. He sighed.

"Hm, maybe I can go chase after him, I have nothing else to do anyways." Seo-Jun said, as he began running in the presumed direction that the killer went. He stopped at a rundown building to catch his breath after running for about 10 minutes. He looked around himself to make sure that no one was following him. Seo-Jun looked at his watch again. "9.30" it read. Seo-Jun decided it would be a great idea to go into the building he was leaning against. He opened the door, which let out a loud creak. as he stepped inside the building and shut the door.

"What the hell was that?" the killer said, grabbing his knife and going behind his door.

"Hello? Anyone here?" Seo-Jun called out, no response. He knocked on the only non-rundown door he saw. The killer slowly opened the door before jumping out and pinning Seo-Jun to the wall, causing him to drop his gun.

"Oh shit, it's you.. you're that detective from earlier.

Seo-Jun looked at the man who was holding him against the wall in surprise as he slowly released his grip on him.

"Come on in, I don't know how you followed me here, but whatever."

Seo-Jun nodded and followed the man into his apartment.

"What is happening???"