Voice of a Murderer

both deals with unsolved case based on real life event, involving children as the victims.

Both are unsolved cases based on a real life event but the plots are completely different.

Both of the stories are fictionalised account based on a real-life unsolved kidnapping case in 1991.

Korean thrillers.
Both about kidnappings.
Father of the child is/becomes the main focus.
[ SPOILER ] The kids end up dying in both.

Both deal with trying to solve a crime around the time the statue of limitations expiring.