Denny's Law

A murder in Tucson on the 4th of July leads to a deadly Arizona crime ring in this "expert police procedural with plenty of quirks and twists" (Kirkus).
Tucson Homicide detective Sarah Burke is just getting used to living with her boyfriend, her fragile mother, and her hard-charging niece Denny, when a baffling murder case consumes their entire household. A man seen fighting in his home during a Fourth of July parade is later found murdered. There's surprisingly little evidence in the house to identify who he was—apart from a gun and large sums of cash.