Calling themselves the #bornfreecrew on Twitter, members of the group closely monitored those whom Mr. Weiner was following, taking it upon themselves to contact young women they believed to be “schoolgirls,” and urging them publicly to stay away from him, according to an analysis of posts on Twitter’s public stream…

But even by the standards of modern politics, Dan Wolfe and other members of the #bornfreecrew watched Mr. Weiner’s account with particular ferocity, and a sharp focus on his interactions with women. In several instances the congressman dropped his online contact with women after they were identified by the crew, suggesting that Mr. Weiner might have been aware of its actions.

There were at least two female high school students among the 191 people Mr. Weiner followed. There is no evidence that he engaged in private discussions with them, and he has said that to his knowledge he has not had any online sexual communications with under-age women…

Mr. Stack said that Mr. Wolfe had told him in a private message that Mr. Weiner had been following a porn star who was later identified as Ginger Lee. “He tweeted about it and then the porn star was gone,” Mr. Stack said. “He was paying attention,” he said, referring to Mr. Weiner.