Billionaire Reid Hoffman has acknowledged that he partially funded a group that used disinformation tactics in Alabama’s 2017 special election in an effort to sink Republican candidate Roy Moore, according to The Washington Post. Last week, Facebook suspended five accounts linked to the operation for “engaging in coordinated inauthentic behavior.” One of those accounts belonged to Jonathon Morgan, CEO of cybersecurity company New Knowledge. Morgan has said he was acting alone as a researcher and not through New Knowledge.

The group Hoffman backed financially, American Engagement Technologies, used Facebook in a manner similar to the way Russia inserted itself into the 2016 US presidential election. They created misleading Facebook pages, urged Republicans in Alabama to support a write-in candidate instead of Roy Moore, and “created false evidence that bots were backing Moore on Twitter” to spur misleading news headlines. The effort was collectively known as Project Birmingham.

“I find the tactics that have been recently reported highly disturbing.”

As The Washington Post notes, Hoffman — an early PayPal executive and co-founder of LinkedIn — has emerged as a big donor to new initiatives and groups with a mission of electing Democrats. But he now regrets backing AET. According to the Post, Hoffman invested $750,000 in the group. On Wednesday, he apologized for having unknowingly contributed to a group that participated in the coordinated campaign. “I find the tactics that have been recently reported highly disturbing,” he told the Post. “For that reason, I am embarrassed by my failure to track AET — the organization I did support — more diligently as it made its own decisions to perhaps fund projects that I would reject.”

“I proudly support aggressive campaigning — both on the ground and digitally — and that is why we’ve funded organizations that help expand civic engagement. But I want to be unequivocal: there is absolutely no place in our democracy for manipulating facts or using falsehoods to gain political advantage,” Hoffman told The Washington Post. “I would not have knowingly funded a project planning to use such tactics, and would have refused to invest in any organization that I knew might conduct such a project.”

Senator Doug Jones, who ultimately defeated Moore by a slim margin, has called for a federal investigation into the matter, a move that Hoffman echoed support for. “What is obvious now is that we have focused so much on Russia that we haven’t focused on the fact that people in this country could take the same playbook and do the same damn thing,” Jones said last Thursday.