Colton 911: Grand Rapids Series by Deborah Fletcher Mello

She’ll do anything to track a killerAnd he’ll do anything to keep her in line…If PI Kiely Colton must work with FBI agent Cooper Winston, she will. But to solve a cold case, she won’t change her break-the-rules style to accommodate the single father’s by-the-book principles. As the investigation progresses, Kiely finds herself inexplicably attracted to her exacting partner and enchanted by his adorable son. Will a ruthless killer put an end to their possible future before it really begins?