Nobody's Mother. Natalie Dvorak Mysteries, #5

Vermont State Police Detective-Sergeant Natalie Dvorak is looking for a suspected killer. The trail leads to an isolated house presided over by "Mother" Frances, a woman with dark secrets. She is prepared to take ruthless action against anyone who might disrupt her home, where she has taken in a small group of senior citizens. Mother Frances and her childlike housekeeper try to hide the truth from Natalie when she visits the house.
Constrained by rules of evidence and haunted by controversy from another murder case, Natalie pushes forward in her investigation, placing herself in more danger than she bargained for, including a deadly game of hide and seek.