"Ultimately, one of the questions I think everybody needs to answer is were those modifications some sort of proximate cause of this event" he said.After it was reported that the limousine in the crash had been cited several times for insufficient braking capacity, defined as having less than 80 percent of the brakes' designed capacity, Frank Figueroa, a California vehicle constructor who had not worked on the Excursion, told NBC News that that failure might have resulted from constricted brake lines.