The Humane Society of the United States faces growing pressure from major donors to cut ties with chief executive Wayne Pacelle after an internal investigation found three complaints of sexual harassment against him.

A number of donors said they would stop funding the Humane Society while others said they would await the results of a board meeting on Thursday that was called to discuss the inquiry into sexual harassment complaints against Pacelle.

Some donors expressed dismay at the Humane Society's decision to leave Pacelle in charge of the organization during the investigation.

"With Mr. Pacelle still at the helm of the organization as the investigation continues, other employees who may have been aggrieved are going to be much less likely to come forward as it would almost certainly appear to them that the alleged perpetrator will still be their boss, and that the Board of Directors is not taking the allegations seriously," Jim Greenbaum, founder of the Greenbaum Foundation, which gave $100,000 to the Humane Society last year, wrote on his Facebook page Tuesday.

"Given the present manner in which the HSUS Board is handling this matter, it is very unlikely that I will continue to fund HSUS."

The Humane Society, one of the country's biggest animal charities, did not respond to requests for comment Wednesday.

Nicole Brodeur, a Portland, Ore., investor who with her husband donated $100,000 to the Humane Society's "Meatless Monday" campaign, said she first heard allegations of sexual misconduct against Pacelle from staff members in October, and decided to stop funding the charity then.

"I spoke with somebody there who had seen incidents of sexual harassment," she said. "I followed up with contacts I had and was horrified. It hadn't occurred to me or my husband to be thinking about workplace culture in our philanthropy decisions."

She added: "It might be time for someone else at the helm."

An investigation by a law firm hired by the Humane Society last month identified three women who complained of sexual harassment by Pacelle. The results of the inquiry were first reported by The Washington Post on Monday.

Senior female leaders told the law firm their warnings about Pacelle's conduct went unheeded for years, according to two people familiar with the matter and a Humane Society memo describing the investigation.

The charity offered settlements to three other workers who said they were demoted or dismissed after reporting Pacelle's alleged behavior, the Humane Society memo said.

Pacelle denied all the allegations Monday. "This is a coordinated attempt to attack me and the organization," he told The Post. "I absolutely deny any suggestion that I did anything untoward."

On the eve of the board meeting, the chief executive defended the effectiveness of the organization and said he was confident of continued support. "I've not gotten one call from a donor who said they're going to stop supporting the organization. I've gotten hundreds that have said the opposite," Pacelle said.

Politico on Tuesday reported complaints of sexual harassment against another prominent animal rights activist at the Humane Society, Paul Shapiro, who reportedly suggested a female employee "take one for the team" and have sex with a donor. Shapiro denies the allegations.

The reports about complaints of sexual harassment against senior leaders caused unease among long-term supporters of the Humane Society.

Several donors called for Pacelle to be fired and objected to the use of the charity's funds to settle personnel complaints.

"I want the money that I donate to go toward helping animals," said Rachel Perman, director of charitable giving and engagement at Tofurky, which makes a vegetarian turkey product.

She said her firm had donated $30,000 to the Humane Society over the past two years. "I don't want to be paying to cover up someone's sexual harassment."

Others supporters said they would no longer volunteer for the organization.

Barbara King, a professor of anthropology at the College of William & Mary, announced in a Facebook post Wednesday that she had resigned from the editorial board of Animal Sentience, a Humane Society journal.

"I'm just getting more angry, and more certain that we all need to keep pushing collectively," she wrote.

Pacelle has headed the Humane Society since 2004 and earned about $380,000 in 2016, according to IRS filings.

He was the subject of an investigation at the Humane Societyfrom Dec. 26 to Jan. 24, according to a memo from the law firm hired to conduct it.

The investigators, who interviewed 33 witnesses, identified complaints from a former intern who said Pacelle had kissed her against her will in 2005, a former employee who said he asked to masturbate in front of her in 2006 and a former employee who said he stopped by her office late one night in 2012 and asked her to salsa dance with him.

The investigation also reported that there was a perception within the Humane Societythat certain women owed their career success to romantic relationships with the chief executive.

Melissa Li, a pathologist in Portland, Ore., and a Humane Society donor since 2012, said reports of Pacelle's actions have left her feeling conflicted because her interactions with the chief executive have been positive.

"But I acknowledge that, well, I'm in a different position," she said. "I'm a donor, not a subordinate."

Li , who did not want to publicly reveal her contributions to the charity, said she wanted to see changes made at the nonprofit, including more transparency around how sexual harassment complaints are handled, before deciding if she wants to keep supporting it. "I believe the women. I really do," she said. "I think they underwent something toxic."