Upon receipt of an envelope containing the absent voter's ballot, the proper officer immediately shall attach the application of the absent voter and file the ballot with other absentee ballots from the same precinct. Before delivering the absentee ballots to the precinct, the proper officer shall package the ballots in a manner so the ballots are sealed securely. The package must be endorsed with the name of the proper voting precinct, the name and official title of the officer, and the words "This package contains an absent voter's ballot and must be opened only according to the processing provisions of section 16.1-07-12." The officer shall keep the package safely in the officer's office until it is delivered by the officer as provided in this chapter.