The District's campaign finance regulators have completed their audit of D.C. Mayor Vincent Gray's 2010 campaign, but they declined to say Monday when they would release the findings of their two-year investigation to the public.

"The final audit report has been completed," the D.C. Office of Campaign Finance said in a report it quietly issued earlier this month. "However, at the request of the U.S. Attorney's Office, additional information may be necessary."

Wesley Williams, an agency spokesman, said the campaign finance regulators did not have a timeline for public distribution of the audit, which the report said was "contingent upon coordination with another enforcement agency."

Bill Miller, a spokesman for U.S. Attorney Ronald Machen Jr., declined to comment on the District's investigation, which took more than two years to complete.

Local authorities began probing the campaign in March 2011 after a minor mayoral candidate, Sulaimon Brown, went public with allegations that he had been paid to remain in the contest and continue his criticism of Adrian Fenty, the incumbent and Gray's rival.

Gray, who has not been charged with a crime, quickly denied wrongdoing and said his campaign had not acted improperly.

But the allegations spurred federal and local investigations, and two of Gray's campaign aides pleaded guilty in May 2012 to charges tied to the scheme.

Thomas Gore, then Gray campaign's assistant treasurer, acknowledged that he shredded a notebook with a record of the payments after investigators began their review. He also pleaded guilty to several campaign finance charges and will face sentencing this summer.

Campaign consultant Howard Brooks pleaded guilty to lying to federal agents. A judge sentenced him to two years of probation last year after Brooks provided extensive assistance to investigators.

The federal probe, however, was not limited to Brown's allegations, and authorities have since detailed a $653,8000 shadow campaign that was designed to enhance Gray's prospects at the polls.

Jeanne Clarke Harris, a longtime operative in D.C. politics, pleaded guilty to charges linked to the shadow campaign in July.

People familiar with the probe, who requested anonymity to discuss the ongoing investigation, have said that authorities believe that Jeffrey Thompson, a prolific campaign donor and city contractor, bankrolled the shadow campaign.

Thompson, whose attorney has refused to discuss the case, has not been charged with a crime, and he has fought prosecutors' efforts to review documents they seized during raids of his home and offices last year.

But as federal investigators continued their work, local authorities repeatedly delayed the release of their report.

In June 2012, Williams told The Washington Examiner that the audit report was "under review subject to final issuance."

But within two months -- after prosecutors detailed the existence of the shadow campaign -- the agency postponed the report's release indefinitely.