Raul Castro is just as bad (if not worse)

The man being tied to a tree by Fidel Castro is a Cuban peasant from the Sierra Maestra. He refused to give his crops to the Cuban revolutionaries, and was "condemned" to execution for refusing. The man covering his eyes is Raul Castro.

Here he is being executed. The man firing the rifle is Raul Castro

The aftermath of the execution - all duly recorded by the camera. The man standing in the background by the collapsed victim is Fidel Castro. The man to the left of Raul Castro is Che Guevara.

And before anyone starts justifying or explaining - this execution (one of many) was well documented by the Castros in the official history of the Revolution - they didn't "back away" from the murder, but used it as an example to those unwilling to cooperate with the regime.