The retirement of Ronal Serpas as superintendent of the New Orleans Police Department leaves much work to do in reforming the troubled NOPD. That challenge must involve not only the new police superintendent but the broader ranks of the city’s leadership and the community at large.

Serpas can claim some successes during his four years as superintendent. The city’s murder rate dropped, perhaps as a result of the department’s collaboration with social service agencies, civic groups and other stakeholders through Mayor Mitch Landrieu’s anti-violence campaign.

Serpas also advanced reforms demanded by a federal consent decree meant to remedy long-standing management problems in the department. Citizen satisfaction with the department increased from 33 percent in 2009 to 60 percent recently, according to the New Orleans Crime Coalition.

But big obstacles continue to nag the NOPD. Staffing levels remain a huge issue, with police manpower declining more than 25 percent since a hiring freeze took effect nearly four years ago. Police officials launched a recruiting campaign last year to replenish the ranks, but results so far have been meager. Although responsibility for the NOPD’s understaffing ultimately rests with Landrieu, the problem obviously compromises any police superintendent’s ability to advance public safety.

Such challenges are a reminder that the city’s security is shaped by factors far beyond the superintendent’s desk. It’s a civic imperative that must involve everyone in New Orleans. That kind of engagement is difficult, though,when the public cannot have a clear view of the department’s operations.

Serpas’ tenure as superintendent also prompted concerns about the department’s commitment to transparency. Critics charged that the nationwide search leading to Serpas’ appointment was all for show, with Serpas already on the fast-track for the job. There also have been questions about the NOPD’s methods for recording crimes.

Lt. Michael Harrison, commander of the department’s 7th District, will serve as interim superintendent.

Landrieu can help strengthen public support for the NOPD by conducting a transparent search for Serpas’ permanent successor. Such support is critical to the department’s future, since no police superintendent, however diligent and talented, can do the job alone.