All dead bodies in the custody of the coroner shall be held until such time as the coroner, after consultation with the prosecuting attorney, or with the police department of a municipal corporation, if the death occurred in a municipal corporation, or with the sheriff, has decided that it is no longer necessary to hold such body to enable him to decide on a diagnosis giving a reasonable and true cause of death, or to decide that such body is no longer necessary to assist any of such officials in his duties.