This is an argument that some critics of Edgar Allan Poe's "The Tell-Tale Heart" have long debated.
Some critics argue that the old man must have known about the narrator’s violent tendencies, for he cries out in horror well before the narrator kills him. Other critics suggest that the old man may have been the narrator’s guardian or even father.
The fact that the narrator only refers to the murder victim as "the old man" is one clue. Sons have referred to their fathers as "the old man" for centuries; the fact that the younger man is living in the same household is another suggestion that he may be living with his father. The murderer (a highly unreliable narrator) claims to have no interest in the man's gold, possibly because he might inherit the man's estate following his death. The murderer claims to "love the old man" and know how the old man feels, and he greets him each morning in his bedroom. Perhaps even the overwhelming guilt that the murderer feels is because of their father-son relationship, and not simply just because he has killed a man with a "vulture-eye."