The local registrar or person in charge of interment or other person having knowledge of the death or fetal death shall refer to the coroner the following cases: (1) where no physician, certified registered nurse practitioner, physician assistant or dentist who is a staff member of an approved hospital was in attendance during the last illness of the deceased or in the case of a fetal death where there was no attending physician, certified registered nurse practitioner or physician assistant or (2) where the physician, certified registered nurse practitioner, physician assistant or dentist who is a staff member of an approved hospital in attendance during the last illness of the deceased or the attending physician, certified registered nurse practitioner or physician assistant in the case of a fetal death is physically unable to supply the necessary data, or (3) where the circumstances suggest that the death was sudden or violent or suspicious in nature or was the result of other than natural causes, or (4) where the physician, certified registered nurse practitioner, physician assistant, dentist or coroner who provided or would provide the medical certification is a member of the immediate family of the deceased. In every instance of a referral under this section, the coroner shall make an immediate investigation and shall supply the necessary data, including the medical certification of the death or fetal death. In no event shall a coroner sign a certificate of death or fetal death for a deceased who was a member of his immediate family.