A Saudi citizen who has spent the past 12 years detained at Guantanamo Bay has been released as the U.S. continues attempts to whittle down the prison population at its base in Cuba.

The Pentagon said Saturday that Muhammad al-Zahrani was sent to his homeland based on the conclusion of a parole-like board that has been re-evaluating whether it is still necessary to hold some of the men as prisoners.

Al-Zahrani will take part in a Saudi rehabilitation program for militants.

He is the 13th prisoner released from Guantanamo Bay this year and the seventh in just the past two weeks. Officials have said there will be additional releases in the coming weeks as part of a renewed push to close the prison where 142 men are now held.