Wikipedia page about this book: https://fr.wikipedia.org/wiki/L%27Affaire_Lerouge

Release date is 2005-04-07

"L'affaire Lerouge" by Émile Gaboriau is a French detective novel published in 1866. When widow Claudine Lerouge is found murdered in her isolated home, two investigations unfold. While the police commissioner pursues a suspicious man with earrings, examining magistrate Daburon and retired investigator Tabaret follow a more promising lead involving a decades-old scandal: an aristocrat's secret child exchange. The key question becomes whether one of these now-adult children killed the widow to prevent damaging revelations about their true identity. (This is an automatically generated summary.)

Original publication data not identified