 After money or merchandise has been stolen, the criminal employs a mule to transfer the money or goods, hiding the criminal's true identity and location from the victim of the crime and the authorities.By using instant payment mechanisms such as Western Union, the mule allows the thief to transform a reversible and traceable transaction into an irreversible and untraceable one.If an innocent third party's bank details have been compromised, they can be used as a mule without their knowledge, something sometimes called "cookoo smurfing".