I admit it! i killed the man! His body is under the floor boards!!
For the rising action when the man was sneaking into the old mans room for the eighth time the old man was awake. He attacked the old man and suffocated him under his own bed. The man than cut off his limbs and hid them underneath the floor boards of the old mans bedroom.
The falling action is when the neighbor heard the old mans scream and called the police and the man said "the scream was of my own I had been dreaming" the police searched the house and found no evidence of a dead body.
The man started hearing a heartbeat. It kept getting louder and louder and it got faster and faster. It was driving the man crazy. He thought the police knew he was suffering and were laughing at him. The heartbeat was from the dead old man. after a bit more suffering the man confessed and yelled. "I admit it I am who killed the man tear up the floor boards!"