Elliot, Kendra. Mercy Kilpatrick novels #4

Series information from author list in front of book ; series numeration from goodreads.com

For FBI agent Mercy Kilpatrick, returning to rural Oregon has meant coming to terms with her roots. Raised as a prepper, Mercy is now relying on her survivalist instincts to defend her town from the people the law can't reach. But this time, an investigation calling up a dark past for her and police chief Truman Daly may be hitting too close to home. A rainstorm has uncovered the remains of five people, a reprise of the distinctive slaughter of two families twenty years ago. Except the convicted killer is in prison. Is this the case of a sick copycat or is the wrong man behind bars? One person might have the answer. The lone survivor of the decades-old crimes has returned to town still claiming that she can't remember a thing about the night she was left for dead. As the search for the truth becomes more dangerous, Mercy fears that the traumatized woman may not have buried her memories at all. She might be keeping them a secret. And there's a price to be paid for revealing them

Sequel to: A merciful secret