Gunfire On The Ranch by Delores Fossen

DEA agent Theo Canton may have been the town bad boy but murder was never his MO. Too bad his girlfriend at the time never saw it that way. Now Ivy Beckett isn't just the girl who broke his heart – she's the target of a killer. Theo vows to keep the blue–eyed beauty safe, even as he meets the son she never told him about. But will it be enough to catch the perp and give their family a second chance?