SAN FRANCISCO >> A senior member of the main U.S. union that represents opera performers resigned today, accusing the leadership of a cover-up in its investigation into accusations of sexual harassment against superstar Plácido Domingo.

Samuel Schultz, a baritone and vice president of the American Guild of Musical Artists, had provided the full findings of the union’s investigation to the Associated Press, which he said AGMA’s leadership had planned to keep secret as part of an agreement with Domingo. Schultz said the deal involved the legendary tenor paying the union a $500,000 fine and issuing a negotiated public apology in exchange for the full details not being disclosed.

The union has said that money would have covered the cost of its 4-month investigation, which involved hiring outside counsel, and funding sexual harassment training. But Schultz called it hush money that did a disservice to the women who stepped forward.

“This is a quid pro quo — silence in exchange for money,” Schultz said in a resignation letter sent Monday to AGMA President Raymond Menard and National Executive Director Len Egert. “I found AGMA’s willingness to bury the details of the investigative report deeply betraying of the women who were sexually harassed by Domingo,” he wrote.

Schultz, who wrote that he was acting “as a sexual assault survivor myself,” provided a copy of his letter to the AP.

In a statement to the AP, Egert denied any cover-up, saying the investigation’s details were kept confidential to protect the identities of people who requested anonymity and that the union’s leaders also felt the settlement could avoid formal disciplinary charges against Domingo that would require an internal hearing.

“Regrettably, due to Mr. Schultz’s admitted breach of confidentiality, the witnesses will now need to determine whether or not they will testify at a disciplinary hearing to prove the charges against Mr. Domingo,” Egert said. The union filed disciplinary charges against Domingo on Friday, initiating a potentially lengthy process that could result in a fine, suspension, censure or expulsion.

The union’s investigation into the sexual misconduct allegations was one of two independent inquiries launched after multiple women accused Domingo of harassment and abusing his power in AP stories published last year. The second inquiry, still ongoing, was launched by Los Angeles Opera, where Domingo had been general director since 2003 before resigning in October.

Last week, AGMA said only that its investigators found Domingo had “engaged in inappropriate activity, ranging from flirtation to sexual advances, in and outside of the workplace.” Based on its findings, the union said, Domingo would “pay fines,” be suspended from the union for 18 months and undergo sexual harassment training.

According to people who spoke to AP on condition of anonymity, the investigation found that 27 people were sexually harassed or witnessed inappropriate behavior by Domingo in the 1990s and 2000s, when he held senior management positions at Washington National Opera and Los Angeles Opera. They said another 12 people told investigators they were aware of the star’s reputation and that it was common knowledge at the two companies.

Schultz’ resignation came after the union launched an inquiry into who leaked the investigation’s findings. In an internal email seen by the AP, Egert and Maynard said the deal fell apart because it “was expressly premised on AGMA’s promise to maintain confidentiality over the details of the investigatory report.”

Last week, Domingo apologized to the women who accused him of misconduct, after denying the allegations for months. “I want them to know that I am truly sorry,” he said. “I accept full responsibility for my actions.”

But two days later, as several Spanish concert halls moved to cancel his appearances, he issued a new statement saying his “apology was sincere and wholehearted,” but had generated a false impression. “I have never behaved aggressively toward anybody, nor have I ever done anything to obstruct or hurt the career of anybody,” he said.

Schultz said in his letter to Egert and Maynard that he felt they had “duped the board into believing Domingo was truly sorry,” adding, “”As Domingo made clear when he retracted his apology, he is unrepentant and continues to believe that he did nothing wrong.”

In 2018, Schultz accused opera star David Daniels and Daniels’ husband, William Walters, of having drugged and raped him in May 2010 after a closing-night party at the Houston Grand Opera. Daniels, who denies the accusation, has since been indicted in Texas on a felony charge of sexual assault.