The Fairfax County police captain in charge of major investigations has filed a defamation lawsuit against Chief David M. Rohrer for e-mails he sent this past spring criticizing the captain and for other actions Rohrer took in response to an anonymous letter alleging internal corruption.

Capt. Denise L. Hopson, 42, oversees the major crimes division of the Fairfax police, including the homicide, robbery and sex crimes detective squads. For a sitting police commander to sue her chief is extremely unusual. Hopson’s attorney, Victor M. Glasberg, advised her not to comment, but he said Hopson did not take the step into court lightly.

“It’s very rough,” Glasberg said. “Denise is in the very rough and uncomfortable position of having to sue her chief and wishes she wasn’t there. She is a loyal and dedicated Fairfax cop. She understands and respects the chain of command, and her professional obligations, and she will abide by them.”

Rohrer and other Fairfax police officials did not immediately respond to a request for comment. The county typically does not discuss pending litigation, police spokeswoman Mary Ann Jennings said.

The chain of events was set off by an anonymous letter that was sent to Rohrer on Jan. 6 and also sent to The Washington Post. The letter claimed to be from “a group of Fairfax County Police Officers who are outraged about the recent process used to select future detectives for the Major Crimes Division.”

Hopson had recently revised the promotion process, her lawsuit says, because the prior system was thought to be unfair. Hopson’s process, including a new written essay requirement, received praise from her commanders, according to the suit.

But the anonymous letter alleged that Hopson manipulated the process to allow a friend to make the list of “highly qualified” candidates for promotion to detective while excluding others with better résumés. In January, lower-level supervisors promoted two officers from the new list to the detective bureau.

Rohrer referred the anonymous letter to internal affairs. Hopson cooperated with the investigation, provided documentation to explain how the process had worked and believed she would soon be cleared, her lawsuit says.

In March, Rohrer decided to invalidate the process and return those already promoted to their previous jobs and said he would transfer Hopson to the police training academy, the chief announced at a command staff meeting, according to the lawsuit and sources familiar with the case. Hopson ultimately was allowed to stay in her job.

On March 7, the chief sent an e-mail to senior commanders saying that the “selection process was unfair and flawed” and that he was going to address it in an e-mail to the entire department. Rohrer added that “the problems primarily center on flawed/poor judgment on the part of the commander running the process.”

Later that day, Rohrer sent a department-wide e-mail announcing the invalidation of the process and the demotion of the two detectives as a result of “clearly a flawed process from a fundamental fairness perspective.”

The internal affairs investigation was still in progress. Hopson alleges in the suit that Rohrer was “willing to take unconsidered, premature and excessive action” toward her because she once complained that he had failed to order a thorough investigation into a male supervisor’s alleged sexual harassment of a female officer.

“Chief Rohrer has never forgiven Capt. Hopson for her challenge to his authority and decision in that case,” the suit says.

Hopson’s suit, filed in Fairfax County Circuit Court, indicates that she also might sue a deputy chief, Maggie DeBoard, because she thinks DeBoard urged Rohrer to act quickly on the anonymous complaint even though the internal affairs investigation was still underway.

In April, the internal affairs probe concluded that the allegations were “not sustained,” the suit says. But Rohrer has declined to sign that finding, the suit alleges.

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