White Night

A pawnbroker is found murdered in a remote town. Police suspect that he was murdered by an acquaintance, as even the most experienced investigator on the case could identify no signs of resistance. Three people come under suspicion, but all of them have perfect alibis, and the investigation comes to a standstill.
One year later, one of them is found dead, and the original murder case becomes even more mysterious. Almost fifteen years pass, and the lead inspector, now approaching retirement, reflects on the only case he could not solve in an otherwise successful career.
Haunted by a sense of responsibility and guilt that he caused suffering by letting the murder case go unsolved, he decides to re-investigate. His persistent search brings attention to the long-forgotten case and reveals a hidden relationship between the victim's son and the neighborhood woman's daughter. As their love grows, more crimes happen. As their sin grows, the inspector's chase comes closer to them.
(Source: RottenTomatoes)
~~ Adapted from the novel "Journey Under the Midnight Sun" (白夜行) by Higashino Keigo (東野圭吾).