Nation IN BRIEF : NEW YORK : Bomb Contents Not Known, Expert Says

An FBI chemist testified that the government does not know the exact composition of the bomb that tore through the World Trade Center last year. It was uncertain whether the admission, which came during testimony at the trial of four defendants in the February bombing, would constitute a critical blow to the government’s case. But it would not appear to help the prosecution’s case, which is attempting to prove the defendants guilty based primarily on scientific and circumstantial evidence. Without the exact composition, prosecutors cannot state that the chemicals found in a storage shed rented by the defendants are the same substances used in the bomb.