Tim Chapman, a Democratic candidate for chairman of the Fairfax County Board of Supervisors, announced Tuesday that he is pursuing an ethics complaint against a rival, a day after revealing he was behind a memo that accused the other candidate of benefiting from a quid pro quo relationship with developers.

Democrat Tim Chapman filed an ethics complaint Tuesday against Jeff C. McKay, who also is seeking the party nomination for chairman of the Fairfax County Board of Supervisors. (Tim Chapman campaign)

An ethics complaint sent by Chapman to Fairfax Commonwealth’s Attorney Raymond F. Morrogh largely echoes the memo about Supervisor Jeff C. McKay (D-Lee), which suggests that McKay helped engineer the 2016 rezoning of a portion of the Kingstowne Towne Center as part of a deal on his home purchase nearly a year later.

A spokesman for Morrogh — whose office doesn’t have investigators — said Chapman would have to bring the complaint to Fairfax police for investigation before the commonwealth’s attorney would potentially get involved.

Chapman argued that it’s Morrogh’s responsibility to investigate the complaint, but he said he would contact the police if necessary.

“If it is determined that our counsel has filed in an incorrect forum, we will immediately file in the correct forum,” Chapman said in a text message.

Chapman is alleging that ­McKay violated Virginia’s State and Local Government Conflict of Interests Act, which, among other things, prohibits public officials from accepting money or gifts in exchange for services performed within the scope of their duties.

An investigation would have to show that McKay used his influence as a supervisor to push through the Kingstowne rezoning application in exchange for a good deal on the five-bedroom home that his close friend, developer Michael A. McGhan, built on land McGhan purchased from the Kingstowne’s owners.

McKay hired his own lawyer to investigate the allegations contained in the anonymously circulated memo, which he called a “borderline libelous” attempt to smear his character. The attorney, Grayson P. Hanes, said he found no connection between the rezoning and McKay’s eventual $850,000 home purchase. Hanes also concluded that the price for the home in the Alexandria section of Fairfax was at market rate.

Chapman alleged in his complaint to Morrogh that the house purchase was “a sweetheart deal . . . from a developer who routinely has dealings before the Fairfax County Board.”

McKay, in a statement, dismissed Chapman’s claims as “a political hack job” and said Chapman, himself a developer, “is using a debunked internet conspiracy theory as a desperate Hail Mary at the end of an election he’s losing.”

The heated back-and-forth reflects the intensity of the current election cycle in Fairfax County, Virginia’s most populous jurisdiction, where all 10 board seats are on the ballot and five of the incumbents are not seeking reelection.

In addition to Chapman and McKay, School Board member Ryan McElveen (At Large) and Alicia Plerhoples, a Georgetown University law professor, are competing in the June 11 Democratic primary election for a chance to succeed longtime board Chairman Sharon Bulova (D-At Large).

The winner will face Republican Joseph Galdo in November.

In the Democratic primary race, Chapman had previously refused to say whether his campaign was behind the memo that was circulated among local officials and news organizations starting in March and focused on McKay’s home purchase.

The Democratic candidates for Fairfax County board chair, clockwise from top left: Tim Chapman, Alicia Plerhoples, Jeff C. McKay and Ryan McElveen. (Tim Chapman; Marion Meakem Photography; Evan Cantwel; Abby Sun)

On Monday, in an article posted by the WTOP news radio station, he was quoted as saying “the memo came from us.”

“That was part of our public records research,” Chapman told WTOP. “There’s no secret about it. I mean, these are very troubling allegations.”

On Tuesday, Chapman told The Washington Post that he decided to come forward because the “public record reveals a clear violation of the Virginia law.” But he wouldn’t say why he initially sought secrecy.

Hanes told The Post last week that he agreed to investigate the claims in the memo on the condition that he would be allowed to draw his own conclusions from land records and interviews. What he found, he said, were loosely connected facts assembled to make it appear that ­McKay did something wrong.

His report to McKay called the allegations “completely baseless.”

In a statement, McKay accused Chapman of deciding “to ignore the real issues in this important election and instead focus on made up, Trump-like personal attacks.”