Complex sentence: Al-Turk was arrested and imprisoned under very difficult conditions from 28 October 1980 to 30 May 1998, spending most of the period in solitary confinement and suffering regular torture.
Split into simpler sentences: Al-Turk was arrested and imprisoned in 28 October 1980 and held under very difficult conditions for almost 18 years. Wright, "Dreams and Shadow," 2008, p.214-5 He spent most of this period in solitary confinement and suffering regular torture.