Mr. Leonard's correct, but just to make sure that you understand what he means by that, no, there is no way that you (or any lawyer, for that matter) can legally require a DA's office to provide any kind of access to their file materials before an indictment has been filed in the case. Most DA's offices, but not all, will provide attorneys access to files pre-indictment, and usually will allow copies to be made of at least the offense report, but Bates stamping is something associated with civil cases, and that's just not going to happen.
Each District Attorney's office has its own policy with regard to pre-indictment discovery. I know of no office that will allow a non-lawyer access to their files.
This opinion is offered for informational purposes only and does not constitute the creation of an attorney-client relationship. You should consult an attorney in person.