The training may have played a role in catching a rapist on the UMass campus at the start of the fall semester. According to a police report and interviews with prosecutors, at 1:16 a.m. on Labor Day, an 18-year-old freshman stopped a young woman heading home alone from a party. Both had been drinking. He pinned her against a tree and began kissing and biting her neck. “I remember his grip around my neck making it harder to breathe,” she told the police. “I was trying to yell but I couldn’t because of the way he had his hands.” After 10 minutes, she was thrown to the ground, her legs “forced open,” her underwear “moved to the side,” and raped.

In the midst of this, two groups of students — a total of eight bystanders, a combination of freshmen and juniors, five women and three men — intervened. (While they have not been identified, it is known that the freshman class had attended a presentation on bystander intervention that holiday weekend and that one of the juniors had been a resident assistant.)

According to the report, one witness used her smartphone to take photos of “a male party, which appeared to be naked from the waist down, on top of a female party,” while others assisted the woman off the ground and out of the immediate area. After making sure she was safe, they called for help and stayed with her until the police arrived and arrested the man.

Patrick Durocher, 18, has been charged with felony rape. He has pleaded not guilty.

The University of New Hampshire has developed one of the most comprehensive research, training and prevention programs in the country and it was spurred, in part, by an equally brutal campus rape back in 1987 when no one intervened.

According to an account in New England Monthly at the time, an extremely drunk freshman was led into a Stoke Hall dorm room by three drunk sophomores who took turns having sex with her. One went into the hallway and bragged that they had a train going, high-fiving his friends. Several students, including the resident assistant, knew what was going on but did not put an end to it. Nor did the roommate intervene as the three boys tried to pressure the girl into saying it was consensual.

The next morning the woman was too drunk to remember, but a few days later, after piecing it together, she filed a complaint with the university. After four nights of hearings before a campus tribunal at a 170-seat lecture hall that was open to the public, two of the boys were found in violation of a university rule called Respect for Others and were suspended for the fall semester. In criminal court, they pleaded guilty to a misdemeanor and spent two months in jail. The third was cleared.

Women on campus, including Ms. Stapleton, the researcher, led protest marches, occupied a dean’s office and at one point surrounded him, linked arms and refused to let him go until he responded to their demands. It took months, but eventually the administration started making the changes that are in place today.