Democrats went out on a limb for Rachael Rollins. To confirm the very prickly, very left-wing prosecutor as US attorney for Massachusetts, they pulled out all the stops, including a tiebreaking vote in the Senate by Vice President Kamala Harris. And how did Rollins repay them? With dishonesty, scandal, and abuse of power.

In two jaw-dropping reports Wednesday, federal investigators from the Office of Special Counsel and the Justice Department’s inspector general detailed Rollins’s flagrant violations of law and ethics in the 16 months since she became US attorney. The watchdog agencies excoriated Rollins for her behavior. To understand why, consider the episode that triggered the investigations.

It occurred in Andover last July. Rollins was about to enter an elegant mansion where a Democratic National Committee fundraiser was being held. A Boston Herald reporter approached. Wasn’t Rollins concerned, the reporter asked, that her attendance would constitute a violation of the Hatch Act, which bars federal prosecutors from engaging in partisan political activity?

“No,” Rollins answered curtly. Then the US Attorney — who was on the clock in her official capacity and had been driven to the event in a government car — entered the reception, mingled for half an hour, and posed for pictures with First Lady Jill Biden, Senator Edward Markey, and others.

When an unflattering story about her attendance at a partisan political event appeared the next morning, Rollins lashed out. “I wasn’t asked for a comment before this ran,” she tweeted — an obvious falsehood. “It’s almost as if the Herald didn’t want to know I had approval.”

That too was false. As the Office of Special Counsel, which investigates violations of the Hatch Act, stressed, not only did Rollins not have approval for what she did, she had been strenuously cautioned not to do it. “That advice,” OSC documented, “came from both her own staff and [Department of Justice] officials in Washington, D.C.”

When her behavior came under investigation, she lied yet again.

“Rollins claimed that she did not attend the fundraiser but instead went to an event related to a US Attorney’s … outreach program, the BRIDGES program,” noted OSC. “But there was no BRIDGES event in Andover that day. And her insistence that she did not attend the fundraiser is wholly contradicted by the evidence.”

In his even more detailed report, Justice Department inspector general Michael Horowitz determined that Rollins was given a clear directive not to do “what she did at the event — to go inside the host’s house during the fundraiser to meet Biden.” When she was called to task, she attempted to pin the blame on her subordinates for not giving her better advice. The inspector general called “Rollins’s efforts to blame her staff for her own ethics failures deeply disturbing,” adding: “We have reason to question Rollins’s claim that she would have followed whatever ethics advice she had been given by her staff.” As the investigation showed, Rollins routinely “ignored the advice she had received from her staff or took certain actions that violated ethics or policy, or showed poor judgment.”

But if her involvement in a political fundraiser was bad, it was nothing compared with her efforts to interfere with the election of her successor as Suffolk district attorney.

Rollins worked strenuously behind the scenes to boost her preferred candidate, Boston City Councilor Ricardo Arroyo. She leaked confidential information from the Justice Department in order to sabotage the campaign of Arroyo’s opponent, incumbent DA Kevin Hayden. Three times she tried to sink Hayden’s campaign by spreading rumors that he would be investigated for possible misconduct. In the words of the Office of Special Counsel, Rollins “repeatedly attempted to sabotage the campaign of a political candidate by leaking non-public DOJ information to the media.” The report described it as “one of the most egregious Hatch Act violations that OSC has investigated.”

Even that doesn’t convey the full extent of her perfidy. When Rollins’s leaks produced a damaging newspaper article about Hayden, top staff members in the US Attorney’s office — who knew nothing of their boss’s involvement — were stricken. The realization that someone was using confidential government information to undermine a candidate in an election was “disturbing and shocking,” they later told investigators. The head of the office’s criminal division was aghast by what the story implied: “Somebody at DOJ is leaking confidential information and … they’re doing it for a partisan purpose.”

Rollins’s reaction was to unleash a flurry of text messages to her senior aides feigning shock at the news story she had planted. “WTF!?!” read one of her texts. Another asked: “Why wasn’t I called? How are they quoting things?”

Repeatedly, the inspector general’s report lambastes Rollins for falling “far short of the standards of professionalism” and the “sound judgment” expected in a US attorney. The Office of Special Counsel, which concluded that her conduct “constitutes an extraordinary abuse of her authority,” could find “no mitigating factors that would warrant an outcome short of disciplinary action.”

Rollins was always controversial. As a radically “progressive” candidate for district attorney, she issued a list of criminal violations that she would not prosecute if elected. Her allies called these “low-level crimes,” but they included such offenses as breaking and entering, larceny up to $250, receiving stolen goods, and malicious destruction of property — offenses that are not “low-level” trivial to their victims.

It was a mistake for the Biden administration to pick Rollins for US attorney — not so much because of her views, extreme though they were, but because of her demeanor and tendency to lash out wildly at anyone who got in her way or disagreed with her. Thus, there was her alleged “road rage” in a shopping center parking lot. Her sweeping radio slander of public defenders as “overwhelmingly privileged” people who don’t care about their “poor, Black, and brown” clients. Her threats to have a TV reporter arrested for asking her a question from a public sidewalk. Her groundless accusation that four district attorneys were motivated by misogyny when they asked to intervene in an important lawsuit.

Between Rollins’s belligerent attitude and Republicans’ unified opposition on ideological grounds, Democrats in Washington took a big gamble when they chose to put everything behind her nomination. Perhaps they hoped she would rise to the occasion, moderate her manner, focus on the job, and surprise everyone by becoming a first-rate US attorney. She turned out to be one of the worst in Massachusetts history. Good riddance to her.