For decades, the New York Police Department was relatively unblemished at the top. Problems arose involving individuals or a single precinct, but its leadership hasn’t been involved in widespread scandal since the days of bribery and corruption in the 1970s. That history, combined with Commissioner Bill Bratton’s reputation as a tough leader with no tolerance for wrongdoing, is what makes the ongoing NYPD scandals so troubling. And it’ll take more than a few arrests to undo the damage, to regain the trust of the public and lower-level officers, and to reform a department that allowed this to unfold.

On Monday, three top NYPD officials were arrested on federal corruption charges. Two commanders were accused of accepting gifts, trips, meals and more in exchange for using the department’s resources to help two NYC businessmen. And a sergeant was charged in another scandal that involved issuing gun licenses in exchange for bribes.

The department’s Internal Affairs Bureau seemed to do its job here, working to police its own since getting its first tip in 2012, which led to Monday’s arrests. But even as investigations continued, officers involved received promotions. That, too, is troubling.

All of this comes as the NYPD fights to restore public trust damaged by other police behavior, potentially even more worrisome, cases like the police-involved death of Eric Garner in 2014. Now, the distrust may grow. After all, if top officers were acting for their own benefit, rather than the public good, why should any of us trust any of them?

This is an onion with many layers — and investigators are still peeling them back. It’s unclear, for instance, exactly whether and how this connects back to Mayor Bill de Blasio, whose fundraising efforts, which included the same two businessmen, are also being investigated. More questions must be answered. But the smell of wrongdoing, corruption and leadership gone bad is permeating the NYPD. Bratton has a lot of work ahead. It’s going to take significant changes to the department’s culture, its connections to the communities it serves and the way officers in power do their jobs. Only then can trust and a focus on the public good seep into the rank and file — and to the public at large.