Section 29. The registrar shall appoint, and for cause, remove, a deputy registrar, chief deputy registrar, assistant to the registrar, and hearing officers, and may delegate to such deputy registrar, chief deputy registrar, assistant to the registrar and hearing officers, the performance of any duty imposed upon the registrar relative to the administration of laws relating to motor vehicles. The registrar may investigate the cause of any accident in which any motor vehicle is involved, and for this purpose may request of the colonel of state police to send his investigators into other states. The police department having jurisdiction over the place or the way where such accident occurred shall notify the registrar forthwith of any fatal accident or accident involving serious injury. The chief officer of the police department of every city and town, the chairman of the board of selectmen of such towns as have no regular police department, or, in the case of toll roads or toll bridges, the chief officer of the police force having jurisdiction to enforce laws relating to motor vehicles thereon, or the chief officer of the police department supervising the accident investigation if two departments have concurrent jurisdiction, shall notify the registrar within fifteen days, in a form prescribed by him, of the particulars of every accident referred to in section twenty-six which happens within the limits of his city, town, or jurisdiction, or on such toll road or bridge, in which a motor vehicle is involved, together with such further information relative to such accident as the registrar may require, and shall also, if possible ascertain the name of the person operating such vehicle and notify the registrar of the same. Every such officer, upon the request of the registrar, shall demand forthwith the license of any operator and the certificate of registration and may take into his possession the number plates of any motor vehicle situated in a city or town within such officer’s jurisdiction when said license or certificate has been suspended or revoked by the registrar and shall forward the said license, certificate and plates to the registrar. Whenever the death of any person results from any such accident, the registrar shall suspend forthwith the license or right to operate of the person operating the motor vehicle in said accident, and shall order the said license to be delivered to him, unless a preliminary investigation indicates that the operator may not have been at fault; and the registrar shall revoke the same unless, upon investigation and after a hearing, he determines that the accident occurred without serious fault upon the part of the operator of such motor vehicle, and shall order the said license to be delivered to him if not already delivered as aforesaid. No operator whose license is revoked or whose right to operate is suspended under this section shall be licensed again nor shall his right to operate be reinstated within six months after the date of the revocation of the license if it was not suspended prior to such revocation, provided, that the foregoing shall not be construed to authorize the exercise of such discretion contrary to any provision of section twenty-four.