From the description:
"When Allison Wallis was beaten to death, Detective Francis X. Loughlin found the killer—Julian Vega, a teenager with a crush on the murdered girl. Using his natural sense of empathy, he cozied up to young Julian, convincing him to give a confession that would put him away until he was thirty-six.
Twenty years later, Julian is finally out of jail, attempting to remember how to live in a world without bars, and Detective Loughlin is still on the job, his sight fading, though his instincts are still sharp. But when Allison’s blood appears at a new crime scene, everything he thought he knew about that long-ago murder is called into question. Was it really Allison they buried? Was Julian actually the killer? And if he wasn’t, who else is in danger now?"