An Unfinished Murder by Jude Deveraux

Sara Medlar may be retired as a bestselling author, but her career as an amateur detective is facing one final mystery-and it's a killer.
Retired romance novelist Sara Medlar has been comfortably sharing her large home with her niece Kate and her "honorary grandson" Jack. It's a convenient arrangement given the Medlar Three, as they've become known, are often working closely together to solve mysteries in their small town of Lachlan, Florida. But when real estate agent Kate announces she's been given the listing for the town's storied Lachlan House, it sets off alarm bells for Sara and Jack. The infamous house has a dark history, one that's certain to haunt them all.
With little memory of her childhood, Kate doesn't understand what the fuss is about-until the trio visits the house and makes a grim discovery. Flooded by memories of the past, Kate realizes she spent time there as a child. But stumbling upon a skeleton dressed in a rotting tuxedo-a murder victim with connections to her father-causes Kate to wonder if the childhood she can't remember might be one she'd rather forget.
As Sara, Kate and Jack delve deeper into the dead man's history, they learn he was last seen at a party held at Lachlan House in the late nineties-a swanky soiree attended by his many enemies. With more than one motive in play, every partygoer is a suspect, and Sara is determined to find the culprit, even if it means digging up past secrets she's worked hard to keep buried.
A Medlar Mystery
Book 1: A Willing Murder
Book 2: A Justified Murder
Book 3: A Forgotten Murder
Book 4: A Relative Murder