The federal investigation of D.C. Mayor Vincent Gray's 2010 campaign has been quiet for nearly eight months, but as the probe nears its second anniversary this week, prosecutors say they remain committed to decoding what they have described as a "corrupted" election.

"The U.S. Attorney's Office is continuing to work with its local enforcement partners on a thorough investigation into activities involving the 2010 mayoral campaign," said Bill Miller, a spokesman for U.S. Attorney Ronald Machen. "Because this is an ongoing investigation, we are unable to discuss any details regarding this matter."

Gray has not been charged with any wrongdoing, and he has denied having knowledge of criminal conduct within his campaign.

But his legal future has been in public limbo since March 2011, when minor mayoral candidate Sulaimon Brown aired allegations that Gray's camp had promised him cash and a job in exchange for remaining in the contest and criticizing then-incumbent Mayor Adrian Fenty at public events.

A grand jury opened an investigation within days.

Authorities have since notched guilty pleas from two Gray aides -- including assistant treasurer Thomas Gore -- for their roles in the scheme.

They also uncovered a $653,800 "shadow campaign," a secret, unreported effort to bolster Gray's political prospects.

Jeanne Clarke Harris, who consulted for Gray's campaign, pleaded guilty last July to charges tied to the plot.

But since Harris' plea, prosecutors haven't charged any others in connection with the shadow campaign, including city contractor Jeffrey Thompson, whom people familiar with the probe have said bankrolled the effort.

"Is it just an open investigation?" asked Ward 7 D.C. Councilwoman Yvette Alexander. "If you haven't found anything, it's time to wrap it up."

And Ward 3 Councilwoman Mary Cheh, who has demanded Gray's resignation, also said she wants a conclusion.

"We can't continue living under a cloud," Cheh said. "[Machen] should either clear people or act against them."

At-large Councilman David Grosso was less critical.

"I want justice served across the board when people have done wrong in the city, and if that's the mayor and other folks, so be it," Grosso said. "But I'm not going to ask Machen to go faster."

Gray has said little about the investigation, and his attorney, while refusing to discuss the probe, noted Gray's successes as mayor while under scrutiny.

"He has done a wonderful job," Robert Bennett said. "He is turning this city around, and people should appreciate what he's done for the city."

Prosecutors may soon face a deadline of sorts: A judge said in December that she was unlikely to delay Gore's sentencing much longer, even though prosecutors said they still needed Gore's cooperation.

He and Harris are scheduled to return to court this month.