Although much of the narrative is focused on him, Santiago Nasar remains a mystery throughout much of the novel. We are told that he was a child of a marriage of convenience and that he is open hearted. His appreciation of valor, prudence, firearms, and falconry, comes from his father, who is no longer alive. We also know that Santiago, had he lived longer, probably would have seduced Divina Flor, just as his father seduced her mother, Victoria Guzman. The narrator gives us somewhat random, fragmentary information with which to piece Santiago together.
The narrative never explains any ambitions Santiago may have had, what motivated him to do things, or whether or not he actually loved his fiancée. The narrator's sister, Margot, tells us that he is handsome and rich, but we are never shown more that these facile, superficial traits. The reader learns that Santiago Nasar frequently dreams about trees, or birds in trees, and that he wakes up with a headache, but we don't know what he dreamed about when he was awake. The narrator seems so focused on collecting others' views of the day of the murder that the narrative neglects to give the reader a comprehensive picture of the victim of the crime.
The narrator strongly implies that Santiago was innocent of the crime, and it does seem clear by Santiago's confused words right before his death that he had no idea what he was being killed for. That he was never seen with Angela Vicario also points to his innocence. But on the other hand, the reader knows that he would have had sex with Divina Flor if given the opportunity, so it is not entirely clear that he would not have been inclined to do so with Angela Vicario if given an opportunity.