The Fairfax County Board of Supervisors yesterday selected Lt. Col. David M. Rohrer to be the county's police chief, following a tradition of selecting chiefs from inside the department but bypassing Acting Chief Suzanne G. Devlin.

Rohrer's appointment ends a five-month search, which included candidates from the District and Jersey City police forces as well as the U.S. Secret Service. Rohrer, a 23-year veteran, heads the department's investigations and operations support branch and was one of three deputy chiefs vying for the vacancy created when J. Thomas Manger retired in January to take the chief's job in Montgomery County.

Rohrer, 47, said his priorities will be preventing gang violence -- a growing problem in the county -- and shoring up the county's preparedness for a terrorist attack. The county's homicide rate is already the lowest among the nation's large localities.

In his interview with the board, Rohrer emphasized his interest in hiring more minorities to reflect the county's changing demographics.

Rohrer was sitting in the audience at the Fairfax board auditorium when Chairman Gerald E. Connolly (D) made the announcement. Devlin and Lt. Col. Charles K. Peters, the other two deputy chiefs and top candidates, were sitting next to him and joined in the applause when Rohrer stood to acknowledge the appointment.

Connolly later called the new chief a "policeman's policeman" who leads with a quiet but "firm and determined" style. "He's a steady hand in times of crisis."

Connolly said the supervisors "went through the pros and cons" of the five finalists. "Dave came in No. 1 in judgment, leadership skills and breadth of experience in the police department," he said. "He's quiet. But he laid out a pretty compelling vision" for the department, Connolly added.

County officials said Rohrer's appointment is effective today. His salary will be $137,000 a year.

The other two finalists were Fairfax police Maj. Tyrone R. Morrow and Donald A. Flynn, an assistant director of the Secret Service. The board interviewed Flynn yesterday after he received strong support from the police union.

The board then deliberated in closed session for more than 21/2 hours before emerging with its decision.

Rohrer, with a quiet, unassuming style, emerged as an alternative to Devlin, who would have been the first woman to head the county's police department. More than a decade ago, she successfully sued the department for sexual discrimination and won a promotion. She also had a protracted zoning battle with the county.

When County Executive Anthony H. Griffin announced her appointment as acting chief in January, Connolly said he welcomed the opportunity to consider making history. But in six months as acting chief, Devlin developed some detractors among the Board of Supervisors, who questioned some of her management decisions, including her recent failure to tell board members of visits planned to the county by Attorney General Jerry W. Kilgore (R) and Rep. Frank R. Wolf (R) to discuss gang violence.

To some county officers, Rohrer's low-key personality made him a slightly surprising selection over a candidate with more visibility and volubility, such as Devlin. But officers and supervisors reacted with excitement that a "cop's cop," as he was repeatedly described, will take over the job overseeing 1,300 uniformed officers and 500 civilians.

"Our membership is pleased with the outcome," said Officer Josh David, president of the Fairfax police union, which had backed Flynn. "Dave Rohrer has a lot of supporters on the police department. A lot of people really look up to him and respect him."

Rohrer, who worked his way up from patrol officer, spent a long part of his career as a tactical officer and then as commander of the special operations division, handling such assignments as hostage situations and search warrants, giving him added credibility with patrol officers, colleagues said. He also headed the Fair Oaks District station and was a commander in the patrol bureau before becoming a deputy chief. As head of investigations and operations support, he oversaw Fairfax's role in the 2002 sniper investigation.

New chief David M. Rohrer, 47, has worked his way up from patrol officer.