One word solves a mystery

A local merchant was preparing to go on a selling trip. After loading his boat he waited on board for his servant. Seeing the merchant waiting alone the boatman decided it would be easy to kill him and steal his goods. The boatman quickly attacked and drowned the merchant and took the goods to his own house. Then he created an alibi. He went to the merchant’s house and asked why he had not come to the boat. The merchant’s wife had all her servants go looking but they could find no trace of him. In time the investigation reached the magistrate who send everyone out the room except the merchant’s wife and asked her for an exact description of the event at the time when the Boatsman first came to ask about her husband.

“My husband had already been gone quite a while”, said the wife, “when the boatman came to our gate and called: mistress why hasn’t the merchant come down yet“.

Next the magistrate talked to the boatman who repeated exactly what he had said when he went to the merchants House.

“That’s it”, the magistrate told the boatman, “The merchant was killed and you are the killer. You just confessed”. “What confession?” protested the boatman.

Do you know what confession?