Complex sentence: Barbie gave his name as Klaus Altmann (the name he had used while in Bolivia) and, claiming that his extradition was technically illegal, made the request to be excused from the trial and return to his cell at St Joseph prison.
Split into simpler sentences: Barbie gave his name as Klaus Altmann (the name he had used while in Bolivia). Claiming that his extradition was technically illegal, he asked to be excused from the trial and returned to his cell at St Joseph prison.