I womder who's that pretty face from chapter 0? The 'my love' part... Red hair detective ...

I think they're the same person mr. Detective has the same natural black hair ( he obviously dyed it red) he also has the same eye shape an eyebrows as oppa

i dont think they are because i think it is the dude that killed the teacher, she had a flashback to that, but you could be right-

If it was the guy that killed the teacher they would have put more attention to the fact that they knew each other but they were strangers to each other when fighting