Why did Starr submit the report, instead of the grand jury?

I am confused! My idea of a Grand Jury is to determine if sufficient evidence exists for an indictment. If this is so, why was the report to Congress submitted by Ken Starr instead of by the Grand Jury? I would think that this method of reporting would be more appropriate - Starr and his team doing the investigating and the Grand Jury themselves making the decision and the report to Congress. Please clarify this point for me.

Response: I think your approach is eminently reasonable and it would certainly be consistent with the idea that the grand jury was in charge of that investigation. The problem, of course, is that the grand jury was not--Starr simply used this grand jury as the vehicle for investigating Clinton's conduct (and that of Lewinsky, et al.) and for gathering evidence that could be turned over to the House Judiciary Committee, in hopes of triggering an impeachment inquiry.

As far as I can tell, the grand jurors played no decision making role in this investigation, aside from, perhaps, deciding to ask certain questions of some witnesses. But in terms of controlling the overall process, I do not think they had any input into that, or certainly no decisive input into that.

It is true that grand juries are supposed to investigate to determine whether someone should be indicted for committing crimes. It is generally understood to be an abuse of the grand jury to use it to gather evidence for use in a civil proceeding (which an impeachment is). The problem, of course, is that one cannot prove Starr was not using the grand jury to investigate the possibility that various persons committed crimes. If charged with that, I suspect he'd say:
(1) we were doing that but didn't find enough to indict anyone; or
(2) we were/are doing that and will be indicting some people in the near future.