In an unprecedented event, D.C. Council members on Tuesday grappled publicly with an ethics investigation into their longest-serving colleague, council member Jack Evans (D-Ward 2).

For nearly five hours, they questioned the findings of lawyers who detailed how Evans repeatedly took official actions during the past five years that benefited his private employers and consulting clients.

Even for a body with a history of corruption scandals, it was extraordinary: the public airing of a probe by a law firm the council hired to investigate one of its own.

Investigators from the firm, O’Melveny & Myers, answered questions for more than five hours that were based on a 97-page report they delivered to the council two weeks ago.

The firm investigated overlaps between Evans’s public service and his private employment at two law firms and a consulting business he started in 2016. The lawyers who led the probe detailed the ways Evans used his office to aid a parking company, developers and a digital sign company that were also paying him hundreds of thousands of dollars for consulting. Evans never disclosed his clients, a violation of the council’s ethics code, the lawyers said.

“We found no evidence there was any traditional consulting work being done other than perhaps talking on the phone or the occasional meeting,” said Steve Bunnell, the lead investigator from O’Melveny & Myers and a former chief of the criminal division at the U.S. attorney’s office for the District.

Council Chairman Phil Mendelson (D) said he emerged from the hearing convinced that “there has been a pattern and practice of violations of code of conduct” and that the investigation was thorough. He has declined to comment on what discipline, if any, Evans should receive.

O’Melveny & Myers was asked by the council to determine whether Evans had violated its rules; the firm made no determination about any possible criminal conduct. Separately, a federal grand jury has been investigating Evans. He has not been charged with any crimes.

Nine of 13 council members have called on Evans to resign. If he does not, the council can censure him, strip him of his remaining committee assignments or expel him — a step that three lawmakers have already said they are willing to take.

Evans, who did not attend Tuesday’s hearing, has refused to step down and disputed the law firm’s findings. He will have an opportunity to address his colleagues about the investigation at a council hearing in early December.

Council member Mary M. Cheh (D-Ward 3), who is leading the council’s investigation into Evans, said there is little appetite from her colleagues to investigate Evans further.

“We already have a lot,” Cheh said.

In a formal response to the report by O’Melveny & Myers, Evans’s lawyers described his assistance to his clients as routine constituent service he would provide to anyone, regardless of whether they were paying him.

The investigators disputed that reasoning, noting that one client was based in Washington state and California, not Ward 2.

“Secondly, they can call anybody else on the council,” Bunnell said. “Third, they don’t need to hire him if they want him to perform constituent services.”

Evans’s legal team has also argued that if he supported a policy or action that was later desired by a client, it’s not a conflict. For example, Evans said it wasn’t problematic to oppose a tax increase on parking lots while representing Colonial Parking because he has consistently opposed tax hikes.

The O’Melveny lawyers disagreed.

“This notion that if you previously supported something it’s not a conflict . . . frankly, that’s just sort of bizarre,” said Bunnell. “It doesn’t make any sense.”

Evans resigned from the board of the Washington Metropolitan Area Transit Authority in June after a similar investigation found he broke ethics rules.

As part of its investigation, O’Melveny & Myers reviewed more than 240,000 pages of documents, including emails, financial arrangements and Evans’s bank records, and interviewed 16 witnesses, including Evans.

But every one of Evans’s consulting clients — except one — declined to speak to investigators, with most invoking their Fifth Amendment right against self-incrimination.

Attorneys for O’Melveny said Tuesday that they were satisfied that they had enough information to reach their conclusions and disputed Evans’s contention that the probe was rushed.

Evans may face a recall vote early next year if elections officials verify that activists submitted enough signatures from registered voters in his district. He has not filed paperwork to run for reelection next year and would face six challengers in the Democratic primary if he does.

Evans has said that the public should consider his decades of service for the District, which includes championing Nationals Park and helping the city government emerge from its financial crisis in the 1990s.

At Tuesday’s hearing, council member David Grosso (I-At Large) said Evans told investigators at-length stories about the D.C. government from the 1990s but couldn’t recall details about the recent private consulting work that threatens to unravel his career.

Bunnell, the lead investigator, paused and smiled.

“The human mind is a mysterious thing,” he said.