HANOVER, N.H. — When a group of graduate students wanted to alert Dartmouth College to sexual misconduct by three professors, David Bucci was the one they turned to.

He was the chairman of the department where the students and professors worked, and he reported the accusation to the college administration.

So he was blindsided when seven female students later named him in a lawsuit against Dartmouth, accusing him of looking the other way and intimidating those who had spoken out.

He grew deeply distressed, his wife and closest colleagues said, especially after he was advised not to complicate the litigation by defending himself publicly. The ordeal eventually brought back the crippling depression he had been treated for years earlier. Some colleagues shunned him. A woman at his food co-op called him a “disgusting human being,” said his wife, Katie Bucci.

In October, 11 months after the lawsuit was filed in late 2018, he took his own life. He was 50.

“I don’t know why he took his life that day, and I’ll never know,” Ms. Bucci said. “But I know that he wouldn’t have gotten to that point had he not gone through that experience with this lawsuit.”

Credit…John Tully for The New York Times

To friends and family members, Dr. Bucci was a casualty of a scorched-earth legal strategy to pin blame on the Ivy League college. They said that they did not question the credibility of the women who came forward, but that his death showed how bit players can be swept up with perpetrators, and badly hurt.

But to the women, Dr. Bucci was a central part of a system that enabled abuse and harassment. He was named 31 times in the 72-page legal complaint, which said that after receiving the initial grievance, the college had been slow to protect the women from further abuse, and that Dr. Bucci had called a department meeting where he browbeat the women who were planning to sue.

The women declined to comment for this article. But one of their lawyers, Deborah K. Marcuse, emphasized that Dr. Bucci had never been accused of carrying out abuse himself. “We are profoundly sad for the family he leaves behind,” she said.

The question of whether Dr. Bucci did all he could to address the misconduct allegations may never be fully resolved. But he did leave behind a trail of emails to friends, family members and colleagues that track his growing anguish over his inability to defend himself and his belief that he was wrongly accused. He and his colleague Thalia Wheatley, the director of graduate studies, who was also named in the lawsuit, struggled to stay silent while the details of the case swirled around campus.

“How does this end in terms of our names being cleared from the wrongful accusations?” Dr. Bucci wrote to a personal lawyer a few days after the complaint was filed. “If Dartmouth settles, can we somehow insist that part of the settlement is that the plaintiffs, in some way, undo what they did to us?”

Justin Anderson, a spokesman for Dartmouth, said the college had fully supported Dr. Bucci. “From the get-go, we viewed Dave as a force for good,” he said.

But he said that the college’s general counsel and public relations office believed that the best way for him to tell his side of the story was not by speaking out but through the legal process, mainly Dartmouth’s point-by-point rebuttal to the complaint. Dr. Bucci was closely involved in drafting that document, he said.

The women’s complaint was filed in November 2018, and it immediately made national headlines for its graphic accounts of rape and harassment.

Dartmouth’s rebuttal was filed in January 2019, long after the news had died down. It got little if any notice.

Shocking Accusations

Before his death, Dr. Bucci spent his days studying rodents in a basement lab on campus, driving there in a pickup truck with a Bernie Sanders sticker on the tailgate. He was a researcher in learning and memory, and took the helm of the psychological and brain sciences department in 2015, for a rotating three-year term.

In April 2017, a group of students met with Dr. Bucci and his close colleague, Dr. Wheatley, to complain about sexual harassment within the department.

At that point, Dr. Wheatley said, the students did not mention some of their gravest allegations, such as rape, and did not name the professors. Still, the accusations were serious enough that she and Dr. Bucci immediately went to the Title IX office, which handles such complaints.

What happened next is a point of debate between the students and the administrators. The students said in their complaint that they were forced to continue working with the professors for nearly four months, allowing the abuse to continue.

Dr. Wheatley said they began taking steps to transfer the students to new labs after reporting their complaint. But the students, she said, asked them to wait to move them because they did not want to tip off the professors until their evaluations were in, for fear of retaliation.

The college put the three professors on leave, and several investigations began.

When the $70 million class-action lawsuit was filed, Dr. Wheatley recalls, she and Dr. Bucci sat in her office flipping through the court papers. The full scope of the accusations sank in.

The three professors — Todd Heatherton, William Kelley and Paul Whalen — “leered at, groped, sexted, intoxicated and even raped female students,” the complaint said. They held lab meetings in bars and invited undergraduates to use cocaine as part of a demonstration of addiction.

Advancement was contingent on compliance, the plaintiffs said, and the professors used their power to force them to participate in an alcohol- and sex-saturated culture. Some students suffered emotional distress. One attempted suicide.

The complaint also implicated Dr. Bucci, Dr. Wheatley and other administrators. They were accused of knowing about the professors’ inappropriate behavior — calling one “handsy” and a “hugger” — but ignoring clear warning signs, for years. They retaliated against the students who came forward, the plaintiffs said, and called a department meeting in October 2018, as the lawsuit was about to be filed, to disparage them.

“We couldn’t even process it, it was so strange,” Dr. Wheatley said.

She said they were being blamed unfairly. Much of the bad behavior took place after hours, off campus, and before Dr. Bucci became chairman. The signs of misconduct had been ambiguous, Dr. Wheatley said. The professor described as a “hugger” would go down the graduation line hugging both men and women. It was considered one of his personality quirks.

“Hanging out at Pine, the local bar, seemed a little weird, but I mean, God, we had no idea” about the pressure the women were under, Dr. Wheatley said.

The lawsuit had come as standards for workplace behavior were rapidly changing. “We’re all savvier now,” she said. “If I saw that now, I would ask more questions.”

Dr. Wheatley said she and Dr. Bucci had called the department meeting to dispel rumors on Twitter that they did not really care about the women, not to go on the offensive. They did not know the women were about to file a lawsuit, she said.

Katherine Alfred, a graduate student in the department who was not involved in the lawsuit, said she could see both sides. “I don’t want to put myself in the position of doubting the victims,” she said. “Things that were intimidating might not have come off as intimidating to me, because I wasn’t directly affected.”

‘I’m Done’

Beyond Dartmouth, the women’s lawsuit helped raise awareness about the potential for exploitation in university departments, where graduate students rely heavily on the mentorship and approval of established professors. Wielding the hashtag #DartmouthDoBetter, students, alumni and faculty members demanded change.

But for Dr. Bucci, the case was deeply personal. He wrote emails to colleagues saying that his health and reputation had been damaged.

He had what he called a “breakdown” about 20 years ago, his wife said, but had been stable with medication and therapy. Now he was having uncontrollable crying fits and waking up in the morning shaking with fear. He was taking drugs for anxiety and depression.

“I’ll be honest, things have been really rough,” he wrote to a friend in January 2019. “The stress has overlapped and affected Katie and the home front as well.”

Colleagues noticed the change. “It was really hard to watch, to be honest,” said Luke Chang, an assistant professor. He seemed to have lost “the sparkle in his eye, all this ambition, the ways he thought he could improve the department.”

On May 1, the plaintiffs added two more women, identified only as Jane Doe 2 and Jane Doe 3, to the class action lawsuit, bringing the total number of named plaintiffs to nine.

The new plaintiffs said that they had been coerced into sexual relationships with two of the professors — one with Dr. Whalen and the other with Dr. Kelley — who threatened them into remaining silent.

Dr. Bucci, according to the new complaint, told Jane Doe 3 that he had always been aware of rumors about her relationship with Dr. Kelley.

Students, alumni and faculty called for Dr. Bucci to be replaced. His emails reflect a sense of defeat.

“I’m done,” he wrote in an email to his sister-in-law, Sarah Hancur. “I honestly just don’t care what happens anymore.”

The faculty dean, Elizabeth Smith, rose to Dr. Bucci’s defense. She sent an email to the faculty saying she had so much confidence in Dr. Bucci that she had extended his term to a fourth year, which was about to end.

Briefly, Dr. Bucci was elated, his wife said. But soon after, he was hospitalized for depression and treated with electroconvulsive therapy.

On Aug. 6, Dartmouth and the plaintiffs announced a $14.4 million proposed settlement, which included reforms that built on steps taken by Dr. Bucci and Dr. Wheatley. Both sides promised to work together to prevent future abuse.

But the agreement did not contain the one thing Dr. Bucci had hoped for: a statement proclaiming his innocence.

A Family in Mourning

The memorial took place in Hanover on a crisp fall day in October. The church, St. Denis, on the edge of the Dartmouth campus, was packed.

At the reception, Dr. Bucci’s 10-year-old daughter, Lila, gave a speech about how her father loved the ocean, the Yankees and going to her brother’s football games. Several people spotted three of the women who had sued among the mourners.

Dr. Heatherton, who was forced to retire, said in a brief interview outside his home recently that he had been shocked by Dr. Bucci’s death and that the lawsuit had been “unfair” to both of them. He said he was glad to be out of what he described as a “toxic” department. The other men, who were forced to resign, did not respond to requests for comment.

Psychiatrists say that it is almost impossible to know why someone took his life, and that Dr. Bucci’s history of depression could have played a part.

After the funeral, the doorbell rang frequently at the Bucci family’s green wood-sided home in Norwich, Vt., five minutes from campus. For days, people came to keep Katie Bucci company. A jumble of rinsed-out Tupperware, to be returned to people who had brought her food, filled the front porch.

Ms. Bucci gave up her job as a science teacher at a community college to raise their three children. She wonders whether she will be able to afford to continue living in the house where her husband laid the plank floors and back patio.

Still, she said she was unwilling to point the finger at anyone for her husband’s death. “Everyone is grappling with this, I’m sure — how this happened, and how they could have stopped it from happening,” she said.

Alain Delaqueriere and Sheelagh McNeill contributed research.