WASHINGTON - US President Barack Obama on Tuesday chose veteran agent Julia Pierson as Secret Service director, the first woman to lead the male-dominated agency, a year after its reputation was tarnished by a scandal involving agents and prostitutes in Colombia.Pierson will replace Mark Sullivan, who retired in February and was in charge during the Colombia scandal - one of the worst in the agency's history.The Secret Service has been criticized for having an insular, male-dominated culture, and Pierson's appointment also comes as Obama fends off criticism that his second-term picks for high-level posts have not included enough women and minority candidates.Pierson, a native of Florida, is currently chief of staff at the Secret Service and began her career as a special agent with the Miami field office in 1983. The director's position does not require confirmation by the US Senate."Julia is eminently qualified to lead the agency that not only safeguards Americans at major events and secures our financial system, but also protects our leaders and our first families, including my own," Obama said in a statement.Starting in 1988, Pierson served four years with the Presidential Protective Division, and she became deputy assistant director of the Office of Protective Operations in 2005.The Secret Service has been trying to rebuild its image after the April 2012 scandal when agency employees in Cartagena ahead of a visit by Obama took prostitutes to their hotel rooms.It led to an official investigation that concluded that the president's safety had not been compromised, but the scandal was a big embarrassment for the agency.A dozen Secret Service employees were accused of misconduct, and at least seven of them have left the agency.Sullivan apologized to Congress last year for the episode, which he said reflected poor decisions by agents and was not representative of the agency's culture. A new code of conduct was implemented banning alcohol use within 10 hours of duty and patronizing "non-reputable" establishments."During the Colombia prostitution scandal, the Secret Service lost the trust of many Americans, and failed to live up to the high expectations placed on it," Republican Senator Chuck Grassley said on Tuesday."Ms. Pierson has a lot of work ahead of her to create a culture that respects the important job the agency is tasked with. I hope she succeeds in restoring lost credibility in the Secret Service."In a statement Tuesday, Sullivan said Pierson would excel in the role. "I have known and worked with Julie for close to 30 years," Sullivan said about his successor. "This is a historic and exciting time for the Secret Service and I know Julie will do an outstanding job."Pierson also received accolades from a key Democrat in Congress. Her appointment "is welcome news and a proud milestone," Senate Homeland Security Committee Chairman Tom Carper said in a statement.Secret Service agents who know Pierson describe her as smart, experienced and even-keeled."Julie was selected because she is competent, and she has been around for 30 years and understands the service well," Ralph Basham, a former Secret Service director, told Reuters."It's exciting for the Secret Service. It's exciting to have a female named to that position. My daughter was a Secret Service agent, so it makes me very proud of the organization and proud of Julie for attaining that position," he said.Law enforcement experts point out that Pierson will not be an anomaly in the broader federal law enforcement community - the heads of the Drug Enforcement Administration and US Marshals Service are women.