Saying that the current investigation into how and why the twin towers fell on Sept. 11 is inadequate, some of the nation's leading structural engineers and fire-safety experts are calling for a new, independent and better-financed inquiry that could produce the kinds of conclusions vital for skyscrapers and future buildings nationwide. Experts critical of the current effort ... point out that the current team of 20 or so investigators has no subpoena power and little staff support and has even been unable to obtain basic information like detailed blueprints of the buildings that collapsed. Some structural engineers have said that one serious mistake has already been made ... the decision to rapidly recycle the steel columns, beams and trusses that held up the buildings. Interviews with a handful of members of the team, which includes some of the nation's most respected engineers, also uncovered complaints that they had at various times been shackled with bureaucratic restrictions that prevented them from interviewing witnesses, examining the disaster site and requesting crucial information like recorded distress calls to the police and fire departments. Members have been threatened with dismissal for speaking to the press.