Killing Orders by Sara Paretsky

V.I.'s battleaxe Aunt Rosa is under investigation by the FBI and SEC after counterfeit stock certificates were found at St. Albert's Priory, where she serves as treasurer. As malicious as her aunt is, V.I. knows she's not dishonest, so V.I. vows to protect her from taking the fall. But V.I. starts questioning the strength of her family ties when a menacing voice on the phone threatens to throw acid into her eyes if she doesn't butt out. The stakes are high as she begins to sniff out a connection between Chicago's most powerful institutions: the Church and the Mob.