It was sangwoo and the dirt was bruises he got from the cop.
That's not dirt honey, its a bruise. Read chapter 35 (づ￣ ³￣)づ
Sorry the guy in the bed was the cop, seungbae
The guy lying on bed is Yang Seungbae, the police man that got fired after everything that happened in S2. He wears glasses, maybe thats why you dont remember him (?).
the one on the bed: isnt it the cop that tried to catch Sangwoo and failed?
btw Sangwoo got beaten up by the cop that's why his face looks like that, this is just after they got back from the police station
who tf was that lying on the bed with the recorder tape thingy ??? also why sangwoo got dirt all over his face