There’s a cloud hanging over Honolulu’s Department of the Prosecuting Attorney, and it is time for its elected chief to do what he can to dispel it.

Keith Kaneshiro is in his third nonconsecutive four-year term as city prosecutor. He should know by now that, while he supervises the agency’s staff, he is accountable to his real bosses: the citizens of Honolulu, including the people who voted for him and those who didn’t.

However, when reports surfaced alleging Kaneshiro received a letter warning him that he’s a target of a federal probe — reported by Hawaii News Now — the elected public official decided that he owes the public little explanation of what’s going on.

He has not acknowledged or disavowed receiving a letter, or said what he’d do to insulate the office from the taint of the allegations. Taking a leave of absence from his post, and insisting that colleagues who have been drawn into the inquiry step away as well, would be the right thing to do.

In response to queries from the Honolulu Star-Advertiser, neither Kaneshiro nor any other agency official would confirm or deny reports that he had received a target letter, or that two top deputies had received subject letters, a noteworthy albeit less-serious alert of federal interest in their actions. They are Chasid Sapolu and Janice Futa, reportedly.

The Prosecutor’s Office issued a written statement Tuesday afternoon asserting that officials do not comment on “investigations any grand jury may or may not be conducting,” citing Federal Rules of Criminal Procedure protecting the secrecy of grand jury investigations. But this does not explain why Kaneshiro can’t speak on the receipt of any letters.

The letters reportedly came from the U.S. Department of Justice, and they would comprise only the latest whiff of trouble wafting through the Prosecutor’s Office.

The office already was touched by the scandal that, over the past few years, had permeated the Honolulu Police Department. That involved charges of corruption and culminated ultimately in the resignations of Louis Kealoha, former police chief, and of his wife, Katherine Kealoha, a deputy city prosecutor.

Kaneshiro himself had come under criticism at that time because he had allowed Katherine Kealoha to remain on staff for a period, despite repeated calls for her to step down.

The reason for those calls then, is the same as now: It will not do to give the public reason to doubt the integrity of criminal cases moving through the Prosecutor’s Office. Kaneshiro ignored that concern then, and so far appears willing to ignore it again.

It is unclear what is going on at the agency, which is responsible for the pursuit of criminal justice in Honolulu, but it can ill afford to invite suspicion of its own integrity.

The principal issue is whether any implication of staff attorneys and officials in malfeasance could compromise cases on which they are working.

Lawyers representing clients under prosecution certainly believe that it could. For example, criminal defense attorney Victor Bakke already told the Star-Advertiser that he is preparing a motion to have a client’s murder conviction reversed because Sapolu had been involved in the case.

“Every case he touches is tainted,” Bakke said.

While it may be too soon to conclude that there is wrongdoing by Kaneshiro, Sapolu or Futa, the prudent action would be to remove any appearance of taint. Kaneshiro could unveil a plan for ensuring that active cases are managed in isolation from any federal probe.

The prosecutorial function of the criminal justice system must be believed, and trusted, by the public to be above board. If it’s not, all the work that it does could be vulnerable to legal challenge. There could be dismissal of cases and reversal of convictions — an injustice to the victims, and to the public that ostensibly a prosecutor protects.

At the moment, Keith Kaneshiro appears interested, principally, in protecting himself.