I pretty much enjoyed all of these, even if they don't fit exactly to what you're looking for, still give them a go!
Voice - Thriller, Mystery, Detective, Investigation
(Drama special) White Christmas - Thriller, Mystery, Psychological, School, Drama, Suspense
Remember: War of the Son - Thriller, Law, Crime, Drama, Melodrama, Investigation
Save Me - Action, Suspense, Thriller, Mystery, Psychological, Drama
Bad Guys - Action, Thriller, Psychological, Crime
Defendant - Thriller, Mystery, Law, Drama, Suspense
The Guardians - Action, Friendship, Thriller, Investigation
Tunnel - Thriller, Psychological, Sci-Fi, Detective
Signal - Suspense, Mystery, Drama, Supernatural, Detective, Investigation
((Probably most OCN dramas will fit what you're looking for tbh))