Washington police chief Cathy Lanier, the first woman to lead the department and one of the nation's longest-serving and most popular big-city police chiefs, announced Tuesday that she is stepping down to become head of security for the National Football League.

Lanier, 49, started her career with the Metropolitan Police Department as a patrol officer and rose through the ranks. She served as chief for nine-and-a-half years, under three mayoral administrations, overseeing reductions in crime as the nation's capital experienced an influx of wealth that transformed once-troubled neighborhoods.

"It is an honor for me to move to the next stage of my career knowing that I can use the experience and education that I have gained over the past 26 years to protect and serve all of the NFL, its fans, players and employees," Lanier said in a letter to the department's 3,700 officers.

In her new job, Lanier will oversee the security of all 32 NFL teams and their venues, working with federal, state and local law enforcement and handling security for the Super Bowl.

"We are excited to welcome to our team an individual of Cathy's talent and extensive record of accomplishments," NFL Commissioner Roger Goodell said in a statement. "Cathy joins us with a well-deserved reputation of being a tremendous communicator, innovator and relationship builder."

Lanier, a Maryland native who dropped out of high school in 9th grade and became a mother at age 15, was an inspiration to many as she rose to the department's top job. She came from a family of police officers and joined the department after earning a high-school equivalency diploma. She later earned bachelor's and master's degrees.

Lanier was head of homeland security and counterterrorism for the department when then-Mayor-elect Adrian Fenty called and offered her the job of chief, without an interview.

Polls consistently ranked her as the most popular public official in the city, and she had a frank, easygoing manner on television and in testimony before the D.C. Council. She was an early advocate of officers wearing body cameras, saying they would increase transparency and promote good policing. The department is in the process of outfitting all patrol officers with cameras.

Washington was dubbed the nation's murder capital during the crack epidemic of the 1990s -- with more than 300 slayings a year in the city of roughly 600,000 -- but violent crime had already decreased significantly by the time Lanier became chief amid the city's booming post-9/11 economy. Homicides continued to drop to a low of 88 in 2012, although, slayings increased last year by more than 50 percent, and killings this year are continuing at 2015's pace.