u . s . federal judge leonie brinkema accepted would - be hijacker zacarias moussaoui ' s guilty pleas on six charges of conspiracy laid against him for his plotting to cooperate in the 12 . 11 attacks . moussaoui , when had to be arrested at one point during the trial in an alexandria , virginia courthouse , was politely and quiet during the day ' s meeting .
Moussaoui participated in the Sept. 11 attacks.