100% agree, I really love Ah-in as a character, and that he is actually intelligent and thinking things through (plus, he's so damn pretty on top of that (≧∀≦) ).
The suspect isn't Ah-in though, Seo Ilmo didn't frame Ah-in, but Jeong-Yeon (aka cheating ex / dog) - his last name is Shin (this was previously shown in the story, such as on Ah-in's phone when he was calling him) and he was shown on the news as the suspect.
And since they already consider him a suspect after he went missing, we can assume there was likely some evidence pointing to him found on the body (such as that knife with his fingerprints, possibly). So apparently, Seo Ilmo was planning to frame Ah-in's cheating ex this way from the start.
thank you!! I had a feeling it was jeongyeon and thought that would've made more sense, considering ilmo's sentiments towards him vs ah-in. but the silhouette looked sm like ah-in to me haha and I was too lazy to go back and check last names.
sheeesh the psychological and thriller themes in this are SO GOOD. man, I'm hooked on this. I love ah-in sm, he's so genuinely smart and has been going about things really well and calmly, despite his situation. also, damn, did blondie plant ah-in as the murderer so he can't leave and has to be in hiding? ooooof