Article 991 of Civil Code

1 - If the mortgagor is a person other than the debtor, execution may not be levied against his property except for what he has mortgaged. He shall not have the right to plead prior recourse against the debtor unless an agreement provides otherwise. 2 - This mortgagor may avert any proceedings directed against him if he relinquishes the mortgaged property in accordance with the procedures and provisions followed by the third-party possessor in relinquishing the property.