With only a single Brunetti novel read, a sample size of less than 5% of this work, it seems to me that the Commissario is fortunate to live and work in Venice. His excessive scruples, and hesitant approach to interviewing and questioning those who might help him unravel the mystery of the death of a mentally handicapped man is matched by the excessive scruples and hesitant approach to providing information by all those who have some knowledge that may unravel a despicable and awful injustice, or in fact might have lead to alleviating the injustice in the first place. A terrible thing was done long ago, compounded by a terrible thing done now, and Brunetti finally has the dubious satisfaction of knowing that the malefactor will not profit by this, rather will suffer grievous loss as a result of their malefaction.
In a typical crime novel set in the United States, I would expect that the police involved in solving a mystery like this would take some action that would be appropriately retributive, but based on my 5% sample I cannot imagine the Commissario being up to that task. He is lucky to live and work(?) in Venice, where his performance, or lack thereof, is acceptable.