The Narrator stalks the old man in the middle of the night to learn his behaviors.
The Eye of the old man gave the narrator extreme anxiety and is the leading reason why the old man is killed. Not for his personality but for his eye that made the "marrow in his bones cold" said the narrator.
After the narrator had been stalking the old man every night for seven days, the narrator decides to open the lantern which makes the old man wakes up when the beam of light hit the 'vulture eye'.
The "vulture eye" bothered the narrator so much to the point where he finally found the right time to kill the old man and put a end to his anxiety.
loud sounds caused the British Colonial Police to come to the old mans house. The narrator is confident in his hiding spots for the body and flaunts the house to the police.
the heart beats (Guilt) to loud and the narrator can no longer hold back the truth from the police, which causes him to fess up.