WHEN Howard Safir steps into police headquarters as the force's new leader, he will become New York's sixth commissioner in less than seven years - one of the most rapid turnover rates for any police department in the nation.
Mr. Safir is Mayor Rudolph Giuliani's choice to replace commissioner William Bratton, who announced his resignation earlier this week. Many law-enforcement experts have credited Mr. Bratton with instituting changes that precipitated a remarkable drop in crime here and with restoring morale to the largest police force in the country.
Like New York, most big-city police departments are accustomed to revolving-door leadership. A 1993 study by the Washington-based Police Foundation found that the average police chief in America's 50 largest cities held the position for just over two years and five months.
Political pressures, budgetary constraints, and high stress have combined to make top-brass departures almost routine. The end result, observers say, is that the 27-month tenure of Bratton is all too typical.
"Turnover in these positions has always been high," says Police Foundation president Hubert Williams. "Particularly in large cities and in the last decade, with the heavy emphasis on crime control. It's a tough job."
For the departments, all the coming and going is a fact of life, says Cynthia Brown, publisher and editor of American Police Beat in Boston. The effect of the revolving door on the department, she says, depends on the circumstances.
Police departments "are quasi-military organizations that often have enormous loyalty, or a kind of intense relationship, to the person at the top," she says. "When they're working for a boss they respect, it's fantastic what goes on. When they're not, it's a different story."
Inevitably, new police chiefs are on a learning curve, especially if they are recruited from outside a department.
"If the chief comes in as a morale booster, he often can overcome that initial hump" of learning to work with the department administration, Mr. Williams says.
For the newly appointed Safir, the learning curve could be steep. Safir, who has served as the city's fire commissioner since early 1994, does not have police department experience. He does, however, have a background in law enforcement: He previously owned a security consulting firm, served in the US Marshal Service, and worked with the Drug Enforcement Administration and the Bureau of Narcotics.
Safir is also a trusted manager of Mayor Giuliani's, a status that may help him to navigate the tricky political waters of chiefdom. Internal politics is generally seen as behind Bratton's March 26 resignation. Bratton, widely credited for whipping New York's corrupt and scandal-ridden force into shape and lowering crime to 1960s levels, was not considered loyal enough to Giuliani. With a mayoral election on the horizon, this was seen as a liability.
Others say loyalty was less an issue than professional jealousy, as Bratton's approval ratings consistently surpassed the mayor's. "This was a story about egos," says Ms. Brown. "The mayor couldn't stand sharing the limelight."
Indeed, politics is largely responsible for high turnover among chiefs of police in large cities.
"It's structural," says Gerald Arenberg, former director of the National Association of Chiefs of Police. "The police commissioner is one of the key positions a winning party has when it comes into office. If the mayor changes, you can be sure the police chief will change, too."
With crime an increasingly sensitive issue, police chiefs often get caught in the crossfire when political points are at stake.
"Crime is a hot-button topic," says Williams. "Look at the way [George] Bush used Willie Horton [in the 1988 presidential election]. If you're in the spotlight, your chances of getting hurt are great."
The formula is simple, observers say. When too much crime is going unsolved or when crime rises, the police chief is the first person people point to. When it falls, everyone takes credit. "If you need someone to blame," echoes Mr. Arenberg, "it's going to be the police chief."
In Los Angeles, the tension between Mayor Richard Riordan and publicly popular Police Chief Willie Williams is no secret. Mayor Riordan has criticized the chief for a lack of leadership.
Riordan, who is up for reelection next year, had vowed not to run again if he hadn't appointed 3,000 new police officers, which have yet to materialize.
Among the department's rank and file in New York, reaction to the latest turnover appears to be mixed.
To one sergeant, who spoke on condition of anonymity, the pending changes won't make much of a difference. "We're the bottom of the barrel here," the sergeant says.
But a patrol officer, a 12-year-veteran of the force, said of the revolving door at headquarters: "In the past, it didn't make a difference. But this guy Bratton really did."