Facebook suspended Cambridge Analytica, a data-analysis firm that worked for U.S. President Donald Trump's 2016 campaign, over allegations that it held onto improperly obtained user data after telling Facebook it had deleted the information.
The whistleblower told the Observer how Cambridge Analytica used personal information taken without authorisation in 2014 to build a system that could profile individual U.S. voters.
"We were forced to take action against Mr. Christopher Wylie to prevent his misuse of the company's intellectual property and he is the subject of restraining undertakings in this regard", the spokesman said. If users had not adjusted their privacy settings on the social media outlet, however, the app didn't just capture the survey responses - it also gathered as much data from each account as possible.
The more than 50 million profiles represented around a third of active North American Facebook users, and almost a quarter of potential USA voters, at the time, the paper said.
Wylie was quoted in The Observer as saying: "We exploited Facebook to harvest millions of people's profiles. That was the basis that the entire company was built on", Wylie told the Observer.
A Facebook spokesperson, meanwhile, said that the data collection was not a hack or a breach.
"In 2015, we learned that a psychology professor at the University of Cambridge named Dr Aleksandr Kogan... violated our platform policies..." The app had been downloaded by 2.7 lakh Facebook users.
It said none of that data was used in the services it provided to Mr Trump's campaign. The Observer investigation also called into question the veracity of evidence given by Facebook and Cambridge Analytica to investigators - not least an official British political inquiry (Byline.com).
Facebook's deputy legal counsel Paul Grewal wrote at length about the decision in a blog post.
The Trump campaign hired Cambridge Analytica in June 2016 to run its data operations.
In total, more than 50 million Facebook profiles were harvested by Cambridge Analytica to build a system to target US voters with political ads, a whistleblower told the papers.
What this means for Facebook: The company says it's still trying to get to the bottom of what happened.
Facebook's announcement on Friday focused on how people affiliated with Cambridge Analytica had violated policies of the social media platform.
"When it subsequently became clear that the data had not been obtained by GSR in line with Facebook's terms of service, Cambridge Analytica deleted all data received from GSR", he said. It says it has data on 220 million Americans, two-thirds of the US population. It was funded by Trump's billionaire donor Robert Mercer, and Bannon once served on its board. The company has likely made some changes since then, such as instituting manual and automated checks on apps using Facebook.
Wylie also commented on the implications of this practice could have for the future.
Some 270,000 people downloaded the app, allowing Kogan to access information such as the city listed on their profile, or content they had "liked". He said the parent company's SCL Elections unit hired Kogan to undertake "a large scale research project in the USA", but later learned that he had obtained data in violation of Facebook policies, and subsequently deleted all data it received from Kogan's company.