The mayor’s office obviously wasn’t happy two weeks ago when former U.S. Attorney Mike McKay told The Seattle Times that he thinks the Department of Justice should fully investigate the Seattle Police Department. Though Mike McGinn says he welcomes such a probe, he and his staff didn’t particularly appreciate McKay’s claim that Police Chief John Diaz was engaged in a “full-blown cover-up” within the department. As the mayor’s attorney Carl Marquardt put it in a January 13 e-mail to McKay and his firm, “You called [Diaz] a liar on the front page of the paper.”

McKay and his brother John, also a former U.S. attorney, had just officially joined the call for a federal civil-rights investigation into the policies and practices of the SPD in the wake of police-related beatings and a fatal shooting. Also seeking a U.S. review is the American Civil Liberties Union and 34 community organizations.

The FBI is set to start a preliminary probe this month, which the McKays hope will widen into a lengthy investigation to cover some of the issues they’ve raised, including an alleged pattern of SPD stonewalling: refusing to release public records involving internal-investigation cases. The McKay firm represents a man allegedly threatened by an armed off-duty police officer during a 2009 incident.

After the January 13 Times story hit the streets and web, Marquardt contacted Mike McKay about his claims. He then sent an e-mail to another of the firm’s attorneys, Pat Preston, asking for clarity. “Can you tell me what is the basis for your claim that Chief Diaz grossly mischaracterized facts?” wrote Marquardt.

Four hours later—a window during which McKay says his firm didn’t have time to respond—Marquardt sent another e-mail, obtained by Seattle Weekly: “John Diaz is an honorable guy. You called him a liar on the front page of the paper, and you’ve got nothing?”

Clearly, Marquardt was ticked off. So was Mike McKay. “We’ve been working on this case 18 months,” says McKay, “and he [Marquardt] gets his back up because we don’t respond in four hours? As you can see, this [the internal investigations] is an institutional problem in Seattle.”

Says Marquardt: “I think it was over-the-top what they are alleging about senior command and a cover-up. The case he’s talking about has gone to court and is on appeal. That’s not unethical. His claim was far beyond the pale.”

One person familiar with the spat says the mayor’s office weighed filing a bar complaint against McKay, but neither side will confirm that. Marquardt says the mayor’s office will soon formally answer McKay’s claims “with a full written response.”