DISTRICT MAYOR Vincent C. Gray was in Charlotte this week, leading the city’s delegation to the Democratic National Convention and acting like it was business as usual. Back in Washington, an assistant U.S. attorney was telling a federal judge that the investigation into Mr. Gray’s mayoral campaign was continuing. The juxtaposition was a reminder of the shadow that hangs over the city government and of Mr. Gray’s failure to address troubling questions about his possible culpability.

It has been more than a year since the U.S. Attorney’s Office opened an investigation into alleged wrongdoing by Mr. Gray’s 2010 mayoral campaign. Sulaimon Brown, a minor candidate for mayor, went public in March 2011 with charges that he was induced to stay in the Democratic primary race and attack Mr. Gray’s main opponent, then-Mayor Adrian M. Fenty, in exchange for money and a lucrative city job. But the investigation expanded beyond those initial allegations with federal authorities uncovering a corrupt “shadow campaign” fueled by tens of thousands of dollars of illegal campaign contributions, allegedly from a D.C. businessman with significant contractual interests with the city government.

Three people associated with the campaign, including two longtime friends of the mayor, have pleaded guilty to felony charges and are cooperating with authorities as they await sentencing. Mr. Gray — who called a news conference to vehemently deny Mr. Brown’s allegations — became more muted as time went by and investigators found evidence to substantiate some of Mr. Brown’s charges. Mr. Gray has denied any wrongdoing but, citing the ongoing investigation, has refused to answer questions.

The result has been an unsettling limbo, with the city’s officials and residents wondering if or when the next shoe will drop. The U.S. attorney typically does not comment on ongoing investigations, but acknowledgment that the probe is continuing came Tuesday during a status conference in U.S. District Court for Thomas W. Gore. He is the former assistant treasurer for the Gray campaign who pleaded guilty to helping to secretly finance Mr. Brown and then destroying evidence of the payments.

Law enforcement authorities operate on no one’s calendar but their own; it’s clearly in the public interest to have careful, methodical investigations. But we hope U.S. Attorney Ronald C. Machen Jr. understands that the continuing unease over city government — heightened by the fact that two members of the D.C. Council, including its chairman, were already forced to resign because of wrongdoing — is corrosive. And we trust that Mr. Gray realizes that it’s hard for the public to have confidence in a mayor who won’t be more forthcoming, particularly one whose election was in part a result of illegal activity.