When an investigation order is issued to determine whether a natural or legal person holds or controls one or more accounts with a banking or financial institution or to obtain information concerning specific bank accounts and banking transactions that have been carried out during a specific period, the magistrate shall state in his request the reasons why he considers that the information requested is likely to be useful in ascertaining the truth and the reasons which lead him to assume that banks located in the executing State hold the account as well as, where applicable, the banks which could be concerned.