(Photo by Paul Morigi/Getty Images for Fortune/Time Inc)

The D.C. Office of Campaign Finance has ordered Mayor Muriel Bowser’s campaign committee to pay a fine of $13,000 after finding more than a dozen campaign contributions over the legal limit.

Bowser’s 2014 mayoral campaign kept $11,771 in excessive donations from 13 individuals and companies, including several deep pocketed developers, OCF found.

The committee has already returned the excess funds to donors and doesn’t plan to appeal the fine, according to the chairman of her 2014 campaign. “Our campaign staff made a mistake, we’re responsible for it,” says Bill Lightfoot. “We’ll accept responsibility for it and pay the fine.”

The order comes just a few weeks after her political protege and successor as Ward 4 councilmember, Brandon Todd, was also fined for a slew of campaign irregularities (he is appealing the findings and $5,100 fine).

Ben Soto served as campaign treasurer for both of Todd’s runs as well as Bowser’s 2014 campaign.

The mayor, Lightfoot says, is “very unhappy” about the errors in her filings. But Lightfoot, for his part, was unwilling to assign blame.

“There are issues with the reports that got filed recently—whether that’s a problem with the staff, whether it was too much work being placed on Ben, it’s unclear,” Lightfoot says. “Before now, his track record was impeccable”

The review was sparked by a complaint filed by the watchdog group Public Citizen, after OCF had already completed and closed out an audit.

“We identified the illegal contributions with a simple sort by address and name of donor. It would have been better if the agency had identified these infractions itself,” Public Citizen said in a statement. A City Paper story from 2015 also seems to have flagged the excessive contributions.

“The mayor has yet to apologize to the public for taking illegal money—that’s the minimum we should expect. Our elected officials should be the first to obey the laws they enact and sign, the mayor as well as the Brandon Todd campaign to the best of my knowledge refuse to admit wrongdoing and apologize in the face of incontrovertible evidence, and it’s unacceptable,” the group wrote.

It is also critical of the size of the fine—half of the amount allowable by law. OCF said it issued the $1,000 fine per violation, as opposed to $2,000, because the campaign already voluntary refunded the excess funds and complied with the investigation.

At this point in time, Bowser’s team isn’t “prepared to say” what went wrong, since several different kinds of mistakes were made. “This is the kind of thing we have to analyze so that we can put changes and improvements in place” for next time, Lightfoot says.

The fine comes at a particularly awkward time for the mayor—just as she gears up for her 2018 re-election bid. Meanwhile, the D.C. Council is also expected to release a report in the coming days on a high-profile firing at the Department of General Services, in which the employee alleges was in retaliation for failing to award a contract to a top Bowser donor, Cuneyt Dil reports.

Bowser’s office did not respond to questions about her position on several campaign finance reform proposals currently before the D.C. Council.

OCF Bowser Order by Rachel Sadon on Scribd