At the opening of the novel Pancho is positive that Rosa was murdered. What evidence does he have to back up his suspicions? How does Pancho's evidence compare/contrast to the police evidence of Rosa's case?
At the start of the narrative, the police have Rosa's dead body and "no sign of foul play." Given this state, they have closed the investigation into her murder. Pancho is committed to finding out more, as he believes she was murdered. Pancho knows his sister and understands her more than the police did. His drive to know more and further investigate what happened to her is a major component of his narrative. Over the course of the narrative, Pancho finds and reads Rosa's diary, in which the presence of a boyfriend is revealed. Pancho also understands that his sister was allergic to alcohol and that alcohol was found in her blood at the time of her death. This revelation and evidence further convinces Pancho that his sister was murdered:
She never drank anything she didn’t pour herself. That’s how I know she didn’t die of natural causes.
In talking with a coworker, Pancho gains more insight through eyewitness testimony as to who the boyfriend was. Pancho confronts him at the end of the narrative and gains his confession as evidence, reflecting a dogged pursuit of the truth behind Rosa's death. Pancho's collection of evidence is more thorough and detailed than what the police gained as it also helps to liberate Pancho from his feelings of anger and violence into a domain where he is willing to "take care of" life.