SEC. 5. Any person who is in the active service and who is officially reported as missing, missing in action, interned in a neutral country, or captured by an enemy, shall, while so absent, be entitled to receive or to have credited to his account the same pay and allowances to which such person was entitled at the time of the beginning of the absence or may become entitled to thereafter: Provided, That such person shall not have been officially reported as having been absent from his post of duty without authority: Provided, further, That expiration of the agreed terms of service during the period of such absence shall not operate to terminate the right to receive such pay and allowances: Provided, further, That should proper authority subsequently determine that the person concerned has been absent from his post of duty without authority, such person shall be indebted to the Government in the amount for which payments have been made or pay and allowances credited to his account in accordance with the provisions of this Act during such absence.