The hugely influential Cult of the Dead Cow, jokingly named after an abandoned Texas slaughterhouse, is notorious for releasing tools that allowed ordinary people to hack computers running Microsoft’s Windows. It’s also known for inventing the word “hacktivism” to describe human-rights-driven security work.

Members of the group have protected O’Rourke’s secret for decades, reluctant to compromise his political viability. Now, in a series of interviews, CDC members have acknowledged O’Rourke as one of their own. In all, more than a dozen members of the group agreed to be named for the first time in a book about the hacking group by this reporter that is scheduled to be published in June by Public Affairs. O’Rourke was interviewed early in his run for the Senate.

There is no indication that O’Rourke ever engaged in the edgiest sorts of hacking activity, such as breaking into computers or writing code that enabled others to do so. But his membership in the group could explain his approach to politics better than anything on his resume. His background in hacking circles has repeatedly informed his strategy as he explored and subverted established procedures in technology, the media and government.