Cole doesn't see any reason to change the city's crime-fighting strategy. "I think the blueprint the commissioner has laid out appears to be working," he said. "The numbers themselves indicate that."

Helen Holton, another City Council member, hopes the mayor chooses a replacement before Bealefeld leaves. "My biggest concern is that we get someone to step into the job and not miss a beat," she said.

The impact of his departure, she said, will "depend on how long it takes to find his replacement and how long it takes that person to blend with our culture." She's not partial to an internal or external candidate but said the person must be "sensitive to diversity and understand the environment here."

City Councilman Brandon Scott, who is 28, notes that Bealefeld "has been a cop three years longer than I've been alive." Scott said that many of the officers who patrolled the streets of Park Heights, where he grew up, are now in the command staff.

He hasn't always agreed with the commissioner, but he said the "difference is night and day" when he compares the crime in his neighborhood now to his childhood, having grown up in the 1990s, when 300 homicides a year was the norm.

"We have too many people who have died to not recognize that progress we've made in this city," Scott said.

Bealefeld's unusually long tenure for a big-city chief gave the department a rare — and welcomed — span of stability, at least in crime-fighting strategy, even as Rawlings-Blake succeeded Sheila Dixon as mayor. Officers endured shifting policies under four different leaders between 2000 and 2007.

Bealefeld's immediate predecessor, Leonard D. Hamm, was pushed out by a mayor angry over high crime and high arrest numbers. Kevin P. Clark was fired after a dispute with his fiancee erupted in scandal, and Edward T. Norris was sent to federal prison for using an off-the-books fund for personal expenses while leading the city force. Before him, Ronald L. Daniel quit after serving just 39 days as commissioner because he didn't agree with the mayor on how to fight crime.

The department went from the perceived soft-policing style of Thomas C. Frazier, who billed himself as a "social worker with a gun," straight into a so-called "zero-tolerance" policy. That filled jails with more than 100,000 arrestees a year, drawing rebukes from judges, as well as lawsuits and complaints that thousands of the arrests for nuisance offenses couldn't withstand even an initial judicial review.

Even with the get-tough style of policing, the number of homicides had remained in the mid- to high-200s, not enough to erase the city's dark image as "Bodymore."

Bealefeld is a hometown boy whose mother hailed from Curtis Bay and father from Hollins Ferry. After dropping out of community college to join the force in 1981 as a patrolman in the Western District, he rose through the ranks and was named commissioner in 2007.

Even before becoming commissioner, he was skeptical of the lock-em-all-up strategy. "I knew there was a better way to do it," Bealefeld said Friday.

He implemented a more nuanced crime plan, a hybrid of zero-tolerance and community policing. He made walks with community groups a centerpiece of the strategy, while ordering officers to target violent and repeat offenders, and to get guns off city streets.

He combined that with straight talk and catchphrases — such as "bad guys with guns." That signature slogan outlined a complex enforcement strategy that actually was the result of painstaking research with criminologists to pinpoint the reasons behind the city's violence.

Bealefeld said that the drop in homicides — 282 the year he started, down to 196 last year — and more importantly, significant drops in non-fatal shootings, reflect his officers making a "cultural change" in policing. The key: targeting the relative few who are responsible for most of the crime.

He argues that armed with fewer police officers and less money than his predecessors, "we went from 100,000 arrests a year to half that number and we got better results."

"It was a testament to what they could get done in this city," Bealefeld said of his cops. "We have incrementally reduced the homicide non-fatal shooting rate these five years. … I'm confident there are a lot of very courageous young men and young women in this Police Department who aren't going to be led away from success."

Some crime experts and community leaders offer a more cautious report card on Bealefeld's tenure, noting the corruption scandals that have continued to trouble the department. Sixteen officers were found guilty in a kickback scheme with a towing company, and an officer was convicted of selling heroin from a station house parking lot.

Another blemish was the fatal shooting of an officer by colleagues at a fight outside the Select Lounge. An independent commission that reviewed the "friendly fire" shooting issued a stinging rebuke of the department's training, and said chaotic on-scene supervision contributed to the officer's death. The criticism struck at the heart of Bealefeld's efforts to better train and professionalize the force.

"There have been some issues behind some of the negative things ... that need to be fixed," said Douglas Ward, director of the Division of Public Safety Leadership in the Johns Hopkins University School of Education.