The human resources operation was considered weak in New York and worse in London, so some employees banded together in solidarity. “If a female executive was asked to go to a meeting solo, she and a colleague would generally double up” so as not to be alone with Mr. Weinstein, recalled Mr. Gill, the former president of Miramax Los Angeles.

Many women who worked with Mr. Weinstein said they never experienced sexual harassment or knew of anyone who did, and recalled him as a boss who gave them valuable opportunities at young ages. Some described long and satisfying careers with him, praising him as a mentor and advocate.

But in interviews, some of the former employees who said they had troubling experiences with Mr. Weinstein asked a common question: How could allegations repeating the same pattern — young women, a powerful male producer, even some of the same hotels — have accumulated for almost three decades?

“It wasn’t a secret to the inner circle,” said Kathy DeClesis, Bob Weinstein’s assistant in the early 1990s. She supervised a young woman who left the company abruptly after an encounter with Harvey Weinstein and who later received a settlement, according to several former employees.

Speaking up could have been costly. A job with Mr. Weinstein was a privileged perch at the nexus of money, fame and art, and plenty of his former assistants have risen high in Hollywood. He could be charming and generous: gift baskets, flowers, personal or career help and cash. At the Cannes Film Festival, according to several former colleagues, he sometimes handed out thousands of dollars as impromptu bonuses.

Mr. Weinstein was a volcanic personality, though, given to fits of rage and personal lashings of male and female employees alike. When a female guest of his had to wait for a hotel room upgrade, he yelled that Ms. O’Connor would be better off marrying a “fat, rich Jewish” man because she was probably just good for “being a wife” and “making babies,” she wrote in her memo. (He added some expletives, she said.) His treatment of women was sometimes written off as just another form of toxicity, according to multiple former employees.

In the fall of 1998, a 25-year-old London assistant named Zelda Perkins confronted Mr. Weinstein. According to former colleagues, she and several co-workers had been regularly subjected to inappropriate requests or comments in hotel rooms, and she was particularly concerned about the treatment of another woman in the office. She told Mr. Weinstein that he had to stop, according to the former colleagues, and that she would go public or initiate legal action unless he changed his behavior.