(CNN) On CNN's "New Day" Friday morning, former independent counsel Ken Starr raised questions about whether current special counsel Bob Mueller might be over-stepping the bounds of his mandate in investigating Russia's meddling in the 2016 election.

Here's the key part:

"I think the gravamen of the original complaint was, was there collusion, to the extent you're moving beyond collusion with Russian operatives or Russian interests or the Russian government itself, and into that which doesn't seem to have a direct tie to Russia, then these questions are in fact raised. It becomes a litigable question that people are going to sidewalk about and disagree about it. I don't think it's clear one way or the other, but i do think it is a certainly a serious matter."

So...

First of all, Ken Starr is the most prominent -- and controversial -- independent counsel ever. If you asked a person on the street to name an independent counsel not named Bob Mueller, Ken Starr would be the only one anyone would come up with. ( Sorry Robert Ray !)

Second, Starr is the reason that all presidents -- Trump included -- are extremely leery of independent or special prosecutors. He is the definitional example of an investigation starting small and growing huge.

Remember that Starr took over the Whitewater investigation, an examination into an Arkansas land deal gone bad, in 1994. By the time Starr released the eponymous report of his findings on Sept. 11, 1998 , his investigation had turned its focus to Bill Clinton's extramarital affair with a White House intern. It took four years and cost roughly $40 million.

Democrats were heavily critical of the expansion of Starr's investigation -- painting him as a partisan prosecutor desperately searching for some wrongdoing by the Clintons. He became the symbol for many Democrats of Republicans' blind hatred for the Clintons -- and helped rally the Democratic base to make history by gaining House seats in the 1998 midterm election.

Starr himself has even turned reflective about the whole thing. "There are certain tragic dimensions which we all lament," he said of his investigation in 2016

Given all of that, for Starr to suggest that Mueller may be out over his skis is ironic. (Worth noting: Starr did praise Mueller as a "man of great integrity as well as enormous experience" in the same "New Day" interview.)

It's important here to note exactly what Mueller's mandate on the investigation actually is. In his order appointing Mueller , deputy Attorney General Rod Rosenstein defined the mission this way:

"The Special Counsel is authorized to conduct the investigation confirmed by then-FBI Director James S. Comey in testimony before the House Permanent Select Committee on Intelligence on March 20, 2017, including:

(i) any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump; and

(ii) any matters that arose or may arise directly from the investigation"

The question, of course, is what definition of "directly" you are using? If you are a Republican, "directly" means only pertaining to things that happened during the 2016 election. If you are a Democrat, "directly" means anything and everything that led up to Russian involvement in the election.

Either way, though, Ken Starr is probably not the guy who should be raising questions about whether Mueller is pushing the boundaries.