D.C. MAYOR Vincent C. Gray (D) now says that he doesn’t remember when he learned of the illegal “shadow campaign” that helped elect him in 2010. No matter, though, because according to the mayor, that is “immaterial.” Mr. Gray’s refusal to acknowledge the importance of the questions that surround his election four years ago won’t make the issues disappear — nor will his empty gestures in the name of being forthcoming.

Mr. Gray’s latest comments about the 2010 campaign, which is the subject of a federal probe, came in an interview with The Post’s Mike DeBonis. An edited transcript of the hour-long session was posted online; it showed the mayor being combative and evasive. “You’re not going to do an interview on 2010. . . . There have been umpteen interviews. . . . There is nothing new, and I don’t see the point of you and me going around and around,” Mr. Gray said at various points.

Mr. DeBonis persisted. He asked the mayor to elaborate on a meeting, held early in the campaign, with the businessman who is alleged to have pumped more than $650,000 into the shadow campaign. Mr. Gray demurred: “I have already addressed that.” In fact, he has not.

What about the allegation by a campaign worker that he raised questions directly with Mr. Gray about the activities of a volunteer who later was found to have run the illegal ground operations? “I don’t recall having that conversation with him,” Mr. Gray said.

As to whether Mr. Gray, as has been reported, declined invitations to meet with the U.S. attorney, the mayor said, “I have nothing further to say about this.”

And so it went, offering graphic representation of Mr. Gray’s notions of cooperation and openness.

D.C. voters, come April 1, will have a chance to decide the credibility of Mr. Gray. We would have hoped that more than 50 percent of D.C. residents in a recent Post poll judging him not to be honest or trustworthy would have underscored the problem that his silence and stonewalling have created. It’s material to D.C. residents to know that they have leaders who will level with them. So far, Mr. Gray has refused.