The Disappearance of Stephanie Mailer — Joel Dicker

Signed
A twisting new thriller from the author of The Truth about the Harry Quebert Affair
In the summer of 1994, the quiet seaside town of Orphea reels from the discovery of two brutal murders.
Confounding their superiors, two young police officers, Jesse Rosenberg and Derek Scott crack the case and arrest the murderer, earning themselves handsome promotions and the lasting respect of their colleagues.
But twenty years later, just as he is on the point of taking early retirement, Rosenberg is approached by Stephanie Mailer, a journalist who believes he made a mistake back in 1994 and that the real murderer is still out there, perhaps ready to strike again. Before she can give any more details however, Stephanie Mailer mysteriously disappears without trace, and Rosenberg and Scott are forced to confront the awful possibility that her suspicions might have been proved horribly true.
What happened to Stephanie Mailer?
What did she know?
And what really happened in Orphea all those years ago?