MANY QUESTIONS remain about the 2010 election campaign of D.C. Mayor Vincent C. Gray (D), which a federal investigation has now definitively described as “corrupt.” Foremost is whether Mr. Gray was aware of the backroom deals, illegal tactics and secret money that helped him beat then-mayor Adrian M. Fenty in the Democratic primary. Mr. Gray has said that he had no knowledge of and no involvement in this “shadow campaign.” But absent a more detailed explanation — which the mayor has refused to provide — that denial lacks credibility.

We do not make this suggestion lightly. We have long hoped that Mr. Gray would provide a better account of his campaign activities, and we repeatedly have urged him to do so. We are not alone in waiting in vain for answers: Voiced on the opposite page is the disappointment of two senior advisers to his campaign in the mayor’s muted public response, which only “raised more questions and further eroded the public’s trust in his administration.” On Wednesday Mr. Gray again declined to answer specific questions, instead offering up the feeble excuse that “this is not the campaign we intended to run.”

Mr. Gray tried to draw a distinction between “issues” in his campaign and his administration. He appears oblivious to the reality that the dishonesty and unlawful acts of the campaign undermine the legitimacy of his election and taint his government.

Here is what has been established in this unfolding scandal. Thomas W. Gore, a close friend of Mr. Gray and the manager of the mayoral campaign’s day-to-day finances, conspired with Howard L. Brooks, a consultant who was close to campaign chairwoman Lorraine Green, to secretly divert Gray campaign funds to fringe mayoral candidate Sulaimon Brown so he could continue his attacks on Mr. Fenty. Mr. Brown was subsequently given a high-paying job in the Gray administration. Both Mr. Brooks and Mr. Gore have pleaded guilty to federal charges.

In addition, $653,000 was secretly and illegally used to buy materials and to hire and equip workers to get people to vote for Mr. Gray, according to this week’s guilty plea by Jeanne Clarke Harris, another person well known to the mayor. The money allegedly came from a prominent businessman identified by Post reporters as Jeffrey Thompson, whose companies had hundreds of millions of dollars in city contracts. One of those contracts was bumped up by millions of dollars shortly after Mr. Gray took office.

There are strong indications that Mr. Gray knew of some contributions from Mr. Thompson. Ms. Harris testified that she gave checks from straw donors to “Co-Conspirator No. 1” — Mr. Thompson — who gave them to Mr. Gray. WRC-TV’s Tom Sherwood reported in March that two sources directly involved with the candidate’s fundraising said that Mr. Gray personally showed up at campaign headquarters one day with as much as $100,000 in contributions from Mr. Thompson and his associates.

Prosecutors have reported that the illegal spending facilitated by Ms. Harris was coordinated with members of Mr. Gray’s campaign and came in response to a request from the campaign for help.

Even if Mr. Gray himself were not involved in those contacts, there are other questions. When yard signs, buttons and other paraphernalia started being delivered to Mr. Gray’s official campaign headquarters, did the candidate not wonder where the items came from, or who was paying for them? Keep in mind these are not inexpensive items; the tab for 5,000 T-shirts was $22,891.26, and 4,250 yard signs cost $17,278. Mr. Gray is not known as someone who delegates, so how to explain this seeming detachment from the guts of his operation?

Another question was framed by D.C. Council member David Catania (I-At Large), who along with colleagues Mary M. Cheh (D-Ward 3) and Muriel Bowser (D-Ward 4) called Wednesday for Mr. Gray’s resignation: “Does any reasonable person believe that Jeff Thompson invested $653,000 in a shadow campaign and didn’t tell the beneficiary? That makes no sense. None.”

Mr. Gray, responding to earlier findings by The Post’s Nikita Stewart that his campaign accepted cash contributions above the city’s legal limit, cited his late entry into the race as a factor. “It was a truncated campaign. . . . It was very chaotic. You had to trust people to run what they were responsible for.” In fact, Mr. Gray was ultimately responsible for the conduct of his campaign. Now he must answer for it.