D.C.-area businessman Jeffrey Thompson pleaded guilty to two conspiracy charges on Monday, after making millions in illegal campaign contributions. The pleas once again cast a spotlight on Washington D.C. Mayor Vincent Gray, who prosecutors allege knew of the shady dealings.

Gray supposedly knew of the “shadow campaign” that Thompson spent $668,000 on for a clandestine voter mobilization effort.

Mr. Thompson said that, contrary to the mayor’s protestations over the years, Mr. Gray was a knowing and active participant in the conspiracy. Together they agreed to refer to Mr. Thompson as “Uncle Earl” to disguise his identity. When the shadow campaign wanted $400,000 for a get-out-the-vote effort, Mr. Thompson insisted that Mr. Gray personally ask for the money, the businessman said; in response, Mr. Gray submitted a one-page budget.

The mayor, up for reelection this year, denied the claims, saying, “I have always been clear that I was not aware of any illegal activity related to my 2010 campaign. I have spent my entire adult life serving the community and have done so with an unblemished record.”

Gray’s primary opponents have already put him on the defensive. City council member Muriel Bowser said, “The citizens of our great city are witnesses to a flagrant betrayal of the public trust.”

Gray’s campaign is just the first of many touched by Thompson’s corrupt funds. Thompson said that more than two dozen campaigns between 2006 and 2012 received his illegal contributions.