At the time, the bombing was the most fatal single event in national law enforcement history, only surpassed later by the World Trade Center terrorist attacks on September 11, 2001 when 72 law enforcement officers representing eight different agencies were killed. Those responsible for the 1917 bombing never were apprehended, but days later, eleven alleged Italian anarchists went to trial on unrelated charges involving a fracas that had occurred two months before. The specter of the larger, uncharged crime of the bombing haunted the proceedings and assured convictions of all eleven. In 1918 Clarence Darrow led an appeal that gained freedom for most of the convicted.