Zero Divergence by Aimee Nicole Walker

Zero Divergence, noun: no deviation from a course or standard.
After a key piece of evidence goes missing, a suspected serial rapist and killer evades prosecution. More than Royce Locke’s reputation is on the line when his investigation into the failed chain of custody suggests Franco Humphries might’ve had inside help. There’s no one Royce trusts more than Sawyer Key to help him right a wrong and uncover the traitor in their midst, but can they do it before the Savannah Strangler strikes again?
Relentless plus fearless equals flawless. Sawyer and Royce have come full circle—from hostile strangers to best friends and lovers. Neither a sniper’s bullet nor an arsonist’s fire could keep them apart, but what about a psychopath hell-bent on revenge? The stakes are high, and there’s no turning back now because the zero hour is upon them. Tick tock.