Sandberg herself has strenuously denied being involved in hiring opposition researchers to plant stories attacking Google and Apple, or to promote false theories about George Soros, the billionaire philanthropist who funds a non-governmental organization called Open Society Foundations (OSF).

Now another Facebooker has taken the fall for hiring Definers, the conservative outfit in question. Late Monday TechCrunch reported on an internal memo by Facebook’s outgoing public policy chief, Elliot Schrage, in which he takes responsibility for hiring Definers to “positively distinguish us from competitors” — but not to pump out fake news.

Definers had urged reporters to examine Soros and OSF’s links with Freedom From Facebook, a coalition that crashed Facebook’s hearing at the House Judiciary Committee in July carrying protest signs depicting Sandberg and CEO Mark Zuckerberg as twin heads of a globe-embracing octopus. There are no such links.

According to the NYT piece, a Facebook employee alerted the Anti-Defamation League about the sign; the Jewish civil rights organization then highlighted the octopus’s nature as a well-known anti-Semitic trope. Zuckerberg and Sandberg are both Jewish. To complicate matters, Soros is also Jewish, and has frequently been the subject of anti-Semitic theories.

“Responsibility for these decisions rests with leadership of the Communications team. That’s me. Mark and Sheryl relied on me to manage this without controversy,” wrote Schrage.

“I knew and approved of the decision to hire Definers and similar firms. I should have known of the decision to expand their mandate. Over the past decade, I built a management system that relies on the teams to escalate issues if they are uncomfortable about any project, the value it will provide or the risks that it creates. That system failed here and I’m sorry I let you all down. I regret my own failure here.”

Sandberg added a note at the bottom of the memo, emphasizing that “it was never anyone’s intention to play into an anti-Semitic narrative against Mr. Soros or anyone else…The idea that our work has been interpreted as anti-Semitic is abhorrent to me — and deeply personal.”

Schrage is on his way out anyway, having announced his resignation in the wake of the Cambridge Analytica fiasco. He is being replaced by Nick Clegg, the former British deputy prime minister, who will apparently review the company’s work with “communications consultants.” Facebook has already cut ties with Definers.

Meanwhile, Zuckerberg defended Sandberg in a CNN interview, saying she was “a really important part of this company and is leading a lot of the efforts for a lot of the biggest issues that we have.”

“She’s been an important partner to me for ten years,” he added. “I’m really proud of the work that we’ve done together, and I hope that we work together for decades more to come.”

The NYT piece hammered Facebook’s share price, with the company’s bad press contributing to a wider rout in tech stocks this week.