At least some Facebook employees were aware of themonths earlier than the company has said it learned about them. The revelation comes as Facebook and the attorney general for Washington, D.C. head to court Friday to argue over whether a document describing employee "speculation" in September 2015 should be made public.
Facebook has asked for the case to be dismissed, arguing that D.C. Attorney General Karl Racine does not have jurisdiction. Racine's office has said the document in question proves it does, because it involves Facebook employees in Washington.
"A D.C.-based Facebook employee warned the company" about Cambridge Analytica data collection practices, according to a motion filed March 18 by the attorney general.
In a statement to CBS News, Facebook acknowledged that the employees mentioned Cambridge Analytica in September 2015.
Facebook executives have said on multiple occasions that they first learned about Cambridge Analytica from media reports in December 2015. A Facebook spokesperson said that timeline remains accurate.
"These were two different incidents: in September 2015 employees heard speculation whether Cambridge Analytica was scraping data, something that is unfortunately common for any internet service," a Facebook spokesperson told CBS News. "In December 2015, we first learned through media reports that Kogan sold data to Cambridge Analytica, and we took action. Those were two different things."
Zuckerberg was asked about the timeline during an April 2018 Senate hearing by Sen. Kamala Harris, a Democrat from California.
"Senator, I don't know if there were any conversations at Facebook overall because I wasn't in a lot of them... I mean, I'm not sure what other people discussed. Our — at the time — in 2015 we heard the report that this developer, Aleksandr Kogan, had sold data to Cambridge Analytica. That's in violation of our terms," Zuckerberg said.
The data sold by Kogan had been harvested from millions of unsuspecting Facebook users, and ultimately directed to Cambridge Analytica and an intertwined company called SCL Group, which provided consulting for the Brexit and Trump campaigns.
The app, called "," allowed Kogan and his business partner Joseph Chancellor to use "psychometric techniques" that would reveal information about individuals "more accurate than even the knowledge of very close friends and family members," according to a contract Kogan signed with SCL Elections.
The revelation that some Facebook employees were aware of Cambridge Analytica has already caught the attention of lawmakers in England, where Facebook is under the microscope for its role in the spread of disinformation and election interference.
"This important new information could suggest that Facebook has consistently mislead...about what it knew and when about Cambridge Analytica," tweeted Damian Collins, the Member of Parliament .