Does divorce occur by the husband's saying "Okay, divorced" after he had previously divorced his wife twice, and more than three months have passed since this statement, knowing that the husband is imprisoned?

If the husband issues three clear divorce pronouncements, his wife becomes irrevocably divorced from him (baynunah kubra), and she is permitted to marry someone else after her waiting period (iddah) has ended. The waiting period for a divorced woman is three months for one who does not menstruate or has despaired of menstruation, and three menstrual cycles for one who menstruates. For a pregnant woman, it ends upon childbirth. If the husband denies the divorce and there is no proof, she should refer the matter to the Sharia court, and she should not marry until her divorce is confirmed.