My thought exactly, wow. I almost freaked out at that scene.
╮(￣▽￣)╭Maybe that what sangwoo had plan if the officer fond out about bum he would be arrested or sangwoo would have killed the officer and hide the body hard to say where to sangwoo hide the body of his past victim anyways Σ(っ°Д °;)っ
This is my perspective so I'm not so sure.... Sangwoo thought that Bum is in the basement (you know how the wardrobe has secret entrance to the basement) that is why he ask the police officer to check in the wardrobe since the police officer is very suspicious of it. The knife was missing because Sangwoo hide it from his back, you actually see Sangwoo reach for his back when the police officer about to open the wardrobe. He basically plan to kill him just in case Bum was still in the wardrobe but fortunately Bum wasn't there><
Still freak me out.
I don't know if this is right but do you think maybe Sangwoo thought Bum was in the wardrobe and told the officer to look so he could just kill him? 'Cause the knife was gone from the counter and I just thought maybe Sangwoo was going to kill the officer when he saw Bum in the wardrobe. I am probably wrong... I just wanna know where the knife went.