It was Mr. Keyes’s behavior toward young women that resulted in measures being taken to insulate them from his advances, according to interviews. That is why he was curbed from the Wall Street Journal’s opinion section, which he frequented to make common cause with its conservatives, in November 2013, according to several Journal employees, including four who said he propositioned them.

The section’s deputy editor at the time, Bret Stephens — now a columnist for The New York Times — said he gave Mr. Keyes a dressing-down, calling him a “disgrace to men” and “a disgrace as a Jew,” and barred him from the office without an appointment.

Mr. Keyes sent email messages to several Journal employees apologizing “for being less than gentlemanly,” as he put it in at least two of the emails.

One of those employees, Kate Havard, was an intern. Mr. Keyes, in late-night text messages, dangled the possibility of having her work for him and asked her to come to his apartment then to discuss it. When she declined, the texts show, Mr. Keyes said he would have to find someone else for the assignment.

Another former Journal writer said that Mr. Keyes had attacked her, pushing her down on his bed and ripping her tights, after luring her to his apartment in November 2012. “He started trying to take off his clothes, while trying to keep me on the bed with one arm,” she said, speaking on condition of anonymity because she is looking for work and fears that being identified as a victim could harm her prospects.

In late 2014, Mr. Keyes was reined in again, this time at the Foundation for Defense of Democracies, a conservative policy group in Washington, according to four workers there, after he made several unwelcome advances to two young female employees, one of whom had been assigned to coordinate his appearance at an event hosted by the organization.

When the two women complained, the foundation imposed a new policy restricting visitors from roaming the offices freely, according to two people who worked there at the time. The foundation confirmed that it had “put in place strict policies and best practices that reflect zero tolerance for harassment or any form of inappropriate behavior.”