Within ten years after judgment in any proceeding had under this chapter, a person not a party or privy to such proceeding may file a petition in the district court showing his claim or right to the property or the proceeds thereof. A copy of such petition shall be served upon the United States attorney at least twenty days before the hearing of the petition, and he shall answer the same. The court thereupon shall try the issue as issues are tried in civil actions, and if it be determined that such person is entitled to the property or the proceeds thereof, the court shall order the property, if it has not been sold, to be delivered to him; or if it has been sold and the proceeds paid into the Treasury, then it shall order that a copy of the judgment be forwarded to the Commissioner of Finance. All persons who fail to appear and file their petitions at any time within the time limited, by law are forever barred, saving, however, to infants and persons of unsound mind the right to appear and file their petitions at any time within the time limited, or one year after their respective disabilities cease.