Can a district attorney request the assistance of investigators or police officers in the presentation of the People's cases?

It may be that district attorneys do sometimes need the assistance of investigators or police officers in the presentation of the People's cases. It may even be that in exceptional cases they could receive assistance from not merely one, but several investigators or officers. The assistance of medical experts or ballistic experts might be desirable at times, but these are not matters for the courts. As the section reads the district attorney has the assistance of the prosecuting witness. The mandate of the statute is clearly expressed in a manner that leaves no doubt as to its purpose. Nothing can be added to or taken from its plain provision except by legislative action. 'If the words of the statute are clear, the court should not add to or alter them to accomplish a purpose that does not appear on the face of the statute or from its legislative history.' People v. Knowles, 35 Cal.2d 175, 183, 217 P.2d 1, 5.