 The continuing criminal investigation created tensions over access to the vehicle, with the National Transportation Safety Board (NTSB), which investigates transportation accidents in order to determine their cause and recommend safety improvements, having complained that the state police did not allow NTSB staff to examine the wrecked vehicle for several months.Larger issues have also been implicated.The NTSB has indicated that it is looking at whether the safety regulations governing limousines, which critics have called particularly lax, are sufficient to protect passengers in light of earlier, less deadly crashes; in September 2019 it issued an interim report on the survival factors involved in the accident that suggested some passengers could have lived if they had worn seat belts, and called on the industry and the state to do more to promote and mandate their use.