Germany's High Court is due Thursday to hear the appeal of Mounir al-Motassadeq, one of only two people convicted of a role in the September 11, 2001 attacks. Motassadeq, who was not arrested until the month after the attacks on New York and Washington, has been tried twice on terrorism charges. He was sentenced in 2003 to 15 years in prison for helping three of the suicide pilots involved in the attacks, then won bail and a retrial. In August 2005 he was jailed for seven years, but released on bail six months later pending the outcome of his second appeal. At both his trials, judges said it was inconceivable he did not know what his associates were plotting. They convicted him of membership in the Hamburg terrorist cell to which the pilots also belonged but dropped charges of accessory to murder at the second trial. Prosecutors are seeking a repeat of the 15-year term handed down at the original trial. The defence wants the verdict overturned on the grounds that there was insufficient evidence to convict him.