RIO DE JANEIRO — Just seven months ago, this city was stunned by images of the lifeless body of Eduardo de Jesus, a 10-year-old boy fatally shot by a police officer on the doorstep of his home. The authorities promised justice to Eduardo’s parents. Protests flared in Complexo do Alemão, the maze of cinder block homes where Eduardo lived.

Then attention to Eduardo’s death subsided, a sign of a crime-weary society somewhat numbed to the thousands of people killed each year by the police. Brazil has far more documented cases of such killings than the United States, where the outcry over such episodes has recently been much more intense.

But Eduardo re-emerged in the national consciousness this month. Investigators have concluded that the police officers involved in his killing were acting in self-defense, reacting to gunfire in their direction from an unidentified shooter.

This version of events directly contradicted accounts by witnesses who contended that there had been no exchange of gunfire.