WASHINGTON, DC – APRIL 1: Mayor Vincent Gray concedes the Mayoral Primary race to Muriel Bowser at the Hyatt Regency in Washington, D.C., on Tuesday, April 1, 2014. (Nikki Kahn/The Post)
Opinion writer

The past four years have produced conclusive proof of rot in the District’s political system. At issue: Have D.C. voters learned the lesson of the 2010 elections that money, greed and grasping politicians don’t mix?

November balloting may tell the tale.

That morally corrupt politicians have flourished in the city is not in question. A rogues’ gallery of political undesirables is available for inspection. In the collection: convicted felons Kwame Brown, the former D.C. Council chairman, and former council members Harry Thomas and Michael Brown.

The gallery also includes ethics offenders. There’s D.C. Council member Vincent B. Orange (D-At Large), the first city official to be formally admonished by the city’s new ethics board for abusing the “prestige of his office” by improperly intervening in a Health Department inspection of a campaign donor’s business.

Orange is joined by council member Jim Graham (D-Ward 1), against whom the ethics board found in 2013 “a substantial body of evidence” that he had violated the city’s code of employee conduct when he intervened in a contract dispute. The board said it didn’t have the authority to penalize him, but Graham was reprimanded by the council and stripped of his oversight of the Alcoholic Beverage Administration because of his transgressions.

Another entry: council member Marion Barry (D-Ward 8), censured and fined $13,600 by the ethics board last year for taking gifts from city contractors. The council also censured Barry for taking the payments from the contractors and stripped him of a committee chairmanship.

The rogues’ gallery doesn’t end there.

Kelvin Robinson and Jeff Smith recently joined the list.

A former council candidate and chief of staff to Mayor Anthony Williams, Robinson pleaded guilty in June to receiving more than $33,000 in illegal contributions from Jeffrey E. Thompson, the D.C. businessman who pleaded guilty in federal court in March to funding a “shadow” campaign to help Mayor Vincent C. Gray (D) win the 2010 mayoral election. Thompson gave Gray’s campaign more than $660,000 in improper donations. Gray has said he did not engage in any wrongdoing and has not been charged with any crime.

Smith, another former council candidate, also pleaded guilty in June to making — with Thompson’s help — a false financial statement to city campaign finance officials during his 2010 campaign. Smith is to be sentenced Thursday.

These guilty pleas are at the heart of moral corruption in the political system. Four years ago, these would-be D.C. Council members sought to conceal from voters thousands of dollars in political spending.

Our collection of rogues may expand before year’s end.

Thompson also spilled the beans on others, including individuals identified in court papers as “Mayoral Candidate A” and “Council Candidate D.” Anyone who thinks U.S. Attorney Ronald C. Machen Jr.’s corruption probe has ground to a halt should think again. In response to my inquiry, Machen’s spokesman William Miller advised by e-mail: “The investigation into campaign spending is moving forward, and the U.S. Attorney’s Office and law enforcement agencies are continuing to make progress.” He said the office would have “no comment regarding the status of specific, uncharged individuals while our investigation continues.”

This thing isn’t over.

And this has a direct bearing on the November elections.

Four years ago, most voters knew little about the extent of illegal money in city politics. Thanks to Machen, we are learning.

But money from special interests seeking to influence D.C. elections and buy — or at least, rent — public officials is still at play. It’s money that eludes city disclosure laws, giving donors an outsize advantage over the individual voter.

Those funds flow through limited liability companies. The so-called LLC loophole allows a company’s owner to get around individual limits by bundling contributions through his or her affiliated businesses.

It has been going on for years, with city lawmakers the chief beneficiaries.

Thanks to dogged reporting by the media, notably WAMU-FM’s Patrick Madden, council members were finally shamed into closing that loophole in the newly enacted campaign finance law.

But get this: The council made certain that loophole closure wouldn’t take effect until 2015.

That delay allowed Democratic mayoral candidates Muriel Bowser (D-Ward 4), Jack Evans (D-Ward 2), Orange and Gray to raise LLC money for the April 1 Democratic primary. As Madden reported, corporate contributions from outside the District poured into the campaign, a lot of them through the LLC loophole.

And again, guess what? LLC money is now flowing into the general election. Don’t believe me? Check out the August financial reports filed with the D.C. Office of Campaign Finance.

The nexus of money and special interest politics remains in play in 2014. Lessons learned: Follow the candidate’s money. Then do something about it.

Read more from Colbert King’s archive.