Karmic Debt by Bob Price

When a violent incident tears open the boundary between the living and the unseen, a hidden cosmic law awakens — the Karmic Debt, a supernatural ledger that demands balance for a murder committed under possession. As past lives bleed into the present and buried identities claw their way to the surface, Anna and Michael are forced into a truth darker than any crime scene.
The police see victims. The universe sees unfinished business.
Haunted by visions, hunted by forces that don’t belong in this world, and bound by a Debt older than their current lives, they must uncover who truly caused the original sin — and why the past has returned to collect.
Some crimes fade. Karmic Debt never does.