In the case of Mr. Worboys, law enforcement officials had assured the women he assaulted that he would never win parole, and that they would be alerted whenever he was considered for it. Both promises were broken, and the women were blindsided by news of his planned release after 10 years in prison.

“I literally felt like somebody had kicked me in the stomach,” one of them said in an interview with the BBC. “As far as I can see at the moment, Worboys could come out of prison tomorrow and live in the house next door to me, and there is nothing I can do to prevent it.”

The case, a topic of daily coverage in the British news media for the last month, has become the subject of sniping between political parties, and even within Prime Minister Theresa May’s fragile governing coalition.

David Gauke, the justice secretary in Mrs. May’s cabinet, said he would not join in challenging the parole ruling in court, a decision that drew harsh responses, including some from members of his own party. Nick Boles, a Conservative member of Parliament, said Mr. Gauke’s stance had shown “a disgraceful lack of spine.”

Victims and some lawmakers from the opposition Labour Party are pressing for new charges against Mr. Worboys, who was prosecuted for a small fraction of the offenses that investigators say he committed. The Crown Prosecution Service has said that it does not plan to bring a new case against him, but critics hold out hope that the service will reverse its position.

Mr. Worboys’s accusers believe he remains dangerous, Ms. Wistrich said. “Some of them are terrified for themselves, their daughters, their neighbors,” she said.

Victims say that Mr. Worboys, a former stripper and pornographic actor, could be charming and persuasive, and they expressed a fear that he had manipulated the parole board.