They Thought He was Safe — P.D. Workman

Zachary Goldman, PI is deeply flawed, unable to overcome much of his traumatic past, yet he is always ready to defend the underdog and right injustices. 

When Pat asked him to look into the disappearance of an illegal, Zachary agreed to take it, but didn't expect to find anything more than a man who had returned to his family or fled immigration officials. But the more he digs, the more missing men Zachary discovers, and it quickly becomes apparent that the disappearance that was deemed by the police not to be suspicious was just the tip of the iceberg.

As the body count grows, so does Zachary's determination to bring the killer to justice, no matter what the cost.

The trouble is, this case might cost him dearly.