The Burning Room (Harry Bosch #17) by Michael Connelly

In the LAPD's Open-Unsolved Unit, not many murder victims die almost a decade after the crime. So when a man succumbs to complications from being shot by a stray bullet nine years earlier, Bosch catches a case in which the body is still fresh, but any other evidence is virtually nonexistent.

Now Bosch and his new partner, rookie Detective Lucia Soto, are tasked with solving what turns out to be a highly charged, politically sensitive case.

Starting with the bullet that's been lodged for years in the victim's spine, they must pull new leads from years-old information, which soon reveals that this shooting may have been anything but random.