ERIC COX and BRENDAN O'BRIEN THE man accused of attacking an Independence Day parade in a Chicago suburb bought his rifle legally, fired more than 70 rounds from a roof and dressed in women's clothing in order to blend into the fleeing crowds afterwards, local officials said. The suspect, 21-year-old Robert E. Crimo III, was taken into custody on Monday after surrendering to police, hours after the attack on the July 4 parade in Highland Park, Illinois, in which six people were killed and more than 30 people were wounded. Officials said at a news briefing that he had planned…