Is a detainee or a convict to shorten his prayers or to offer them in full?

A detainee or a convict does not shorten the prayer unless he is a traveler. If he is a traveler and was unjustly imprisoned, he is permitted to shorten the prayer according to the Hanbalis. According to the Hanafis, a traveler who is imprisoned due to debt shortens the prayer, unless he is wealthy and intends to repay the debt. According to the Malikis, a traveler remains a traveler as long as he has not formed the intention to reside [permanently]. According to the Shafi’is, the ruling of travel ceases with the intention to reside for four days.