Special counsel Robert Mueller's team is reportedly studying the relationship between the Trump campaign and Cambridge Analytica, the global data firm that has been embroiled in controversy in recent days over its use of personal Facebook information.

ABC News reported Wednesday that digital experts who worked to support President Trump's White House bid have met with Mueller's team of investigators. Those staffers worked closely with Cambridge Analytica, which the campaign used during the 2016 contest.

The Trump campaign declined to comment to ABC News.

Mueller previously requested all emails from employees at Cambridge Analytica who worked with the Trump campaign. The request, reported in December, was voluntary.

Cambridge Analytica was suspended from Facebook on Friday after reports it had not fully deleted data it obtained from Cambridge University professor Aleksandr Kogan. The professor was found to have harvested more than 50 million Facebook profiles from his app, which required a Facebook login. The data firm reportedly used the information to create "psychographic" profiling tools, underpinning its work for the Trump campaign.

Cambridge Analytica has denied it mishandled Facebook data. However, the firm suspended its CEO on Tuesday after a London media outlet published a video that showed him discussing the use of bribes and prostitutes to sway political elections.

The company's board said in a statement it is conducting an independent investigation, and that CEO Alexander Nix's comments "do not represent the values or operations of the firm."

Facebook founder Mark Zuckerberg on Wednesday acknowledged that the company had made past "mistakes" but emphasized several steps the social media platform has or plans to take amid the crisis to protect users' data.

Updated at 4:41 p.m.