The New York Attorney General’s Office subpoenaed over a dozen different telecommunications lobbying groups on Tuesday to help determine whether they were behind an estimated 9.5 million fraudulent comments posted in support of the rollback of net neutrality, according to a report from The New York Times.

The investigation was launched last November, only a month before the Federal Communications Commission was set to vote on a proceeding that would roll back the open internet regulations instated under the Obama administration. Millions of comments were filed prior to that vote, and according to the attorney general’s office, 9.5 million of those may have been fraudulent.

“The FCC’s public comment process was corrupted by millions of fake comments — and our investigation found that as many as 9.53 million of those comments stole the identities of real people,” AG Barbara Underwood said in a statement. “My office will get to the bottom of what happened and hold accountable those responsible for using stolen identities to distort public opinion on net neutrality.”