D.C. Council member Jack Evans (D-Ward 2), seen in Washington on June 18, is stepping down as Metro board chair after an ethics probe. (Jahi Chikwendiu/The Washington Post)

WHEN METRO was confronted in 2012 with serious concerns about the involvement of a board member in a controversial real estate deal, it responded in a serious way: It hired an internationally renowned law firm. It conducted an independent investigation that amassed more than 18,000 pages of sworn testimony and documents. A 62-page report was produced and released. Metro officials voted unanimously to accept the report’s findings of misconduct. Metro officials held a news conference and answered questions.

It was, in short, a master class in thoroughness, transparency and government accountability. Clearly, though, the lesson didn’t stick, as evidenced by the complete hash the Metro board has made of its inquiry into Metro board chairman Jack Evans. “Surreal” is how The Post’s Robert McCartney described the board’s investigation of Mr. Evans’s conduct, but other words — including “incompetent” and “unacceptable” — also come to mind. With Mr. Evans set to leave the board and a new chairman slated to be chosen Thursday, the board’s first priority must be to reestablish credibility and public trust.

That will require a full airing by the board of the investigation by the ethics committee into allegations that Mr. Evans (D), also the District’s Ward 2 council member, used his public office to advance private interests. The committee hired a law firm to conduct an investigation but instructed that there be no written report or minutes of the committee’s deliberations. The rationale for secrecy was that the 2012 report detailing misconduct by former board chairman Jim Graham factored into a lawsuit against Metro that resulted in a settlement for the developer who had claimed wrongdoing. It is sad that the board’s takeaway from those unsavory events was not an emphasis on ethical behavior but rather the cynical conclusion that as long as nothing was written down or made public, there were no problems.

The law firm that conducted the probe into Mr. Evans wrote an internal memo about its findings 13 days after the ethics committee closed the investigation. The memo later became public, but that’s insufficient. The firm should present its findings in public. Mr. Evans should have an opportunity to respond and answer questions. The four members of the ethics committee must explain their reasoning and their actions. Why did they think it would be fine to conduct and close an investigation into such a prominent public official with no explanation to the public? One of the members of the committee, Paul Smedberg of Virginia, is expected to be selected the board’s new chairman, and another, Corbett Price of the District, falsely said the committee had found no violations when, in fact, it had cited Mr. Evans for failing to disclose a conflict of interest. What exactly is Mr. Price’s explanation for that misreporting? Should the public have confidence in Mr. Smedberg? What needs to be done to improve the board’s operation?

Just as Mr. Evans’s integrity has been called into question, so has the board’s. Particularly at a time when Metro itself is improving its operations and gradually winning back public trust, its governing board should not be allowed to drag the system down. The public needs answers.