Pennsylvania Attorney General Kathleen Kane invited her aide to her home on a Friday night and offered him a beer from the wet bar.

That was the end of the hospitality.

Ms. Kane instructed Kevin Wevodau, a former FBI agent and one of her office’s top investigative commanders, to leave his cell phone on a table some distance from where they spoke, so nothing could be recorded.

Then, she told him he was a “cancer” on the office, that he was the leaker behind a host of negative stories about her, that she knew he would be a witness against her in court.

She told Mr. Wevodau he should resign. If he didn’t, she warned, his reputation “could be ruined” and he could “lose his family.”

This unusual confrontation last June between boss and subordinate is laid out in a lawsuit newly filed by Mr. Wevodau, who refused to quit and has been in professional limbo ever since. The seventh such suit filed against Ms. Kane or her agency, the lawsuit is the chronicle of an aide who quickly went from ally to outcast in an office awash in paranoia and ill will.

Chuck Ardo, a spokesman for Ms. Kane, said the office had not had a chance to review the suit, filed in Commonwealth Court, and thus had no comment.

When Ms. Kane took office in 2013, the first Democrat and woman to serve in the elected post, she brought in a new leadership team. She appointed three men to supervise the office’s investigative agents, paying each about $140,000 annually.

She named Mr. Wevodau to oversee criminal investigations, David Peifer to manage child predator cases and Jonathan Duecker to run narcotics investigations.

Now, Mr. Wevodau is on unwanted, if paid, administrative leave, and Mr. Peifer has been granted immunity from prosecution to testify against Ms. Kane at her upcoming criminal trial. Only Mr. Duecker remains a Kane confidant, serving as acting chief of staff as well as narcotics chief.

Ms. Kane promoted Mr. Duecker despite a recommendation from her human resources unit that he be fired for allegedly sexually harassing an agent and a prosecutor. Ms. Kane’s agency later accused the official who made that recommendation of leaking to reporters, and fired him. He, too, is suing her.

At the time of Mr. Duecker’s promotion, a critic of the move said Ms. Kane told him, “He’s loyal. I don’t have anyone left who is loyal to me.”

As for Mr. Wevodau, 58, he joined Ms. Kane after working for three decades as an FBI agent, including a final stint commanding the agents who broke the so-called “kids for cash” judicial scandal in Luzerne County.

Fairly early on, Mr. Wevodau says, he complained to Ms. Kane that she seemed to prefer to pass orders to him through her driver, rather than directly.

Ms. Kane didn’t take the criticism well, the suit says. She replied by accusing Mr. Wevodau of being a “mole for the FBI.”

But as with so many former and current staffers with the attorney general’s office, it was his involvement with a controversial sting investigation inherited by Ms. Kane and later disavowed by her that ended up casting him most deeply into disfavor.

Ms. Kane shut down the undercover investigation in 2013 without bringing charges, although the sting had caught six elected officials from Philadelphia on tape pocketing money.

She later gave confidential documents to a newspaper in a bid to embarrass a former state prosecutor whom she blamed for leaking the news that she had aborted the sting case. That leak and what prosecutors say were her subsequent lies under oath about her actions are the basis of her pending criminal trial. Ms. Kane, who faces charges of perjury, conspiracy and other crimes, has denied any wrongdoing.

Pressed to explain why she shuttered the sting, Ms. Kane said Mr. Wevodau had written up notes in 2013 reporting that the operation’s case agent had told him he had been instructed to target only African-Americans.

Ms. Kane’s statement turned out to be half true.

Although Mr. Wevodau did make such a charge in a memo, he produced the memo in 2014 — four days after Ms. Kane told the public she already had it.

In the memo, released several months ago as pretrial evidence in Ms. Kane’s criminal case, Mr. Wevodau is critical of the sting. But his suit downplays that, wrongly suggesting it had raised doubts about the racial-targeting claims.

Dismissing any suggestion that race played a role in the sting, he writes instead that Ms. Kane killed the probe “to maintain or gain political allies and serve her own political career goals.”

The case agent, Claude Thomas, has denied telling Mr. Wevodau that race played any role in the sting. He sued Ms. Kane and Mr. Wevodau last year, but Mr. Wevodau was granted immunity from suit.

In the aftermath of the sting controversy, Mr. Wevodau testified in grand jury investigations focused on Ms. Kane’s leaking and on her handling of the sting.

In December 2014, he says, one of Ms. Kane’s closest allies, Renee Martin, who served for a time as a Kane spokeswoman, questioned him about the matter, demanding to know whether he had become a witness against the attorney general. Ms. Martin declined to comment Monday.

Judges overseeing both grand jury probes issued protective orders barring Ms. Kane from taking retaliatory action against witnesses. This may help explain why Ms. Kane pressed for Mr. Wevodau to resign but did not fire him.

On the Monday after the Friday meeting at Ms. Kane’s home north of Scranton in June 2015, Mr. Wevodau applied for medical leave.

By last fall, he was ready to return to work. But he says Ms. Kane has refused to let him come back, leaving him on paid administrative leave.

First Published: April 5, 2016, 4:00 a.m.