A helicopter that was carrying the CEO of one of Nigeria’s largest banks and five others left a shallow crater and a trail of debris when it crashed in Southern California’s Mojave Desert earlier this month, according to investigators with the National Transportation Safety Board. The agency on Friday released a preliminary investigation report into the Feb. 9 deadly crash. Flight tracking data analyzed by investigators shows the helicopter was heading in a southeasterly direction as it gradually descended in altitude and increased in ground speed before the crash.