(CBSNEWS.COM) – A prominent data analytics firm that worked with President Trump’s campaign exploited Facebook data to harvest “millions” of profiles of U.S. voters without their authorization, according to a whistleblower who once worked to help acquire the data. On Friday, Facebook announced Cambridge Analytica — the firm that was created by billionaire donor Robert Mercer, previously run by Steve Bannon, who went on to become White House chief strategist, and received $5.9 million from Mr. Trump’s 2016 presidential campaign — has been suspended for violating the social media company’s standards and practices.

Christopher Wylie, who worked to help obtain the data, told Britain’s The Observer that Cambridge’s entire operation was designed to “exploit” what they knew about people from their profiles and “target their inner demons.”

READ MORE: Christmas Tree Lighting Takes Place At Klyde Warren Park In Dallas Saturday, December 4

Cambridge Analytica specializes in “psychographic” profiling that allows them to predict the voting likelihoods of individual people based on personality — and Facebook is a treasure trove for information like that.

“We exploited Facebook to harvest millions of people’s profiles,” Wylie told the British news outlet. “And built models to exploit what we knew about them and target their inner demons. That was the basis that the entire company was built on.”

In a statement Friday, Facebook acknowledged that it learned it had been “lied to” about Cambridge Analytica and an affiliate’s activities in 2015, more than two years before suspending the firm from its platform, but did not alert users at the time. The Observer reported that Facebook made only minor efforts to secure the information of more than 50 million people. Facebook insists there was no breach of their system.

Facebook acknowledged that it learned at the time that University of Cambridge psychology professor Aleksandr Kogan “lied to us and violated our platform policies” by passing data from an app that lets people log in using their Facebook account to Cambridge Analytica and Eunoia Technologies Inc.’s Wylie.

Facebook says Kogan requested access for his personality predictor app “thisisyourdigitallife.” Facebook said that in 2015 it removed the professor’s app and demanded the destruction of all information acquired — which Cambridge Analytica, Kogan and Wylie all certified that it destroyed.

But several days ago, the social media company said, it learned that perhaps not all data had been destroyed. Facebook says it is still investigating those claims. The New York Times also reported that copies of the data harvested for Cambridge Analytica still existed online, and reporters accessed the raw data.

In a statement, Cambridge Analytica said it “fully complies with Facebook’s terms of service and is currently in touch with Facebook following its recent statement that it had suspended the company from its platform, in order to resolve this matter as quickly as possible.” The company also said it deleted all information.

READ MORE: Wrong Way Crash On I-30 Kills At Least One In Fort Worth

“In 2014, we contracted a company led by a seemingly reputable academic at an internationally-renowned institution to undertake a large scale research project in the United States,” Cambridge said in a statement. “This company, Global Science Research (GSR), was contractually committed by us to only obtain data in accordance with the UK Data Protection Act and to seek the informed consent of each respondent. GSR was also contractually the Data Controller (as per Section 1(1) of the Data Protection Act) for any collected data. GSR obtained Facebook data via an API provided by Facebook.”

Cambridge Analytica also said that “no data from GSR” was used by Cambridge as a part of services it provided to Mr. Trump’s campaign.

“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. We worked with Facebook over this period to ensure that they were satisfied that we had not knowingly breached any of Facebook’s terms of service and also provided a signed statement to confirm that all Facebook data and their derivatives had been deleted. No data from GSR was used by Cambridge Analytica as part of the services it provided to the Donald Trump 2016 presidential campaign. Cambridge Analytica only receives and uses data that has been obtained legally and fairly. Our robust data protection policies comply with US, international, European Union, and national regulations.”

A spokesman for Cambridge Analytica also said the firm refutes the stories from the Guardian, which is associated with the Observer, and the New York Times, and rejects Wylie.

“We refute the claims made by The New York Times, The Guardian, and their source, a former contractor to the company, Mr Christopher Wylie (“Mr Wylie”), in what is patently a malicious attempt to hurt the company,” the spokesman told CBS News. “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. It is clear that he has a grudge to bear and appears set on trying to damage the company.”

Mr. Trump’s presidential campaign spent $5.9 million in five payments on Cambridge Analytica from June 2016 through December 2016, according to Federal Election Commission (FEC) records. But his campaign wasn’t the only one. The presidential campaign of Sen. Ted Cruz, R-Texas, spent nearly as much — $5.8 million — on the data analytics firm.

Special Counsel Robert Mueller is also interested in Cambridge Analytica, as his team investigates Russian election meddling and any ties to the Trump campaign, The Wall Street Journal reported Friday. The newspaper reported Mueller asked the firm to hand over internal records. Social media sites and Facebook specifically were prominent tools in Mueller’s indictment of 13 Russians accused of leveraging fake social media accounts to influence the 2016 presidential campaign.

MORE NEWS: Plumber Finds Cache Of Money Behind Loose Toilet In Wall At Joel Osteen's Lakewood Mega-Church

© 2018 CBS Interactive Inc. All Rights Reserved.