Dirty Genes — Marci Martin

The fifth Hannah Pryce series mystery, Sara Mills, a hospice patient, claims Hannah's ex-husband, Sam, who passed on some years before, fathered her son and asks Hannah to care for the boy. One by one, six hospice patients are murdered, including Sara. An exhaustive search for the boy's father, with the aid of DNA, includes a long list of men, since Sara, an alcoholic, had many affairs. Hannah's detective husband, Dave, heads the search for the killer, who threatens the lives of everyone in the hospice, including Dave and his partner, Greg. And time is running out for all of them.