Blood Sister by Kenna McKinnon

Annie Hansen, a schizophrenic private eye, is tasked with solving the murders of the town mayor and a local doctor in the small town of Serendipity, Canada.

Together with handsome detective Mark Snow, they set to bring the killer to justice. But Annie is haunted by her past, unable to overcome the darkness she's been carrying for her whole life.

Soon, the investigation takes a surprising turn when Annie and her boyfriend find themselves among the suspects. What is the cryptic message left on the late doctor's charts, and who is responsible for the crimes?