The madman lives in the old man's house and he states that he is not crazy.
The madman was bothered by the old man's evil eyes.
Every night, for 7 days, the madman went to the old man's room while he was sleeping waiting for him to open his vulture eye.
OKAY! I DID IT!
On the 8th night, the old man wakes up because he heard the madman's noises. The old man decides it was time to kill him since he started listening to the old man's heart beats and thought that the neighbors were going to listen.
When the madman kills the old man, he starts cutting the old man's body parts and places them on the wooden slabs.
The police arrived, and he starts listening to someone's heart beats and he got really nervous so he confessed his crime.