"Dear Mr Nix… thank you for your letter of 27 March agreeing to appear before the Committee to give further oral evidence. We would like to hold this session on the morning of 17 April," Collins said in a letter to Nix that he subsequently posted on Twitter.
Collins posted another letter, to Facebook, asking that the company's CEO Mark Zuckerberg appears before the committee.
READ MORE: 'Not Conducive to Democracy’ — Cambridge Analytica Whistleblower
The CEO of data analysis firm was first questioned by the panel on February 27 about Cambridge Analytica's role in Brexit campaign and their use of Facebook, as part of the committee's ongoing investigation of fake news.
However, earlier this month, Facebook suspended the accounts of Cambridge Analytica and the SCL group it belongs to as it emerged that a third-party application had transferred users' information to them, which is forbidden by the social network's rules. The information then may have been used for political campaigning.
Nix was suspended in March after a Channel 4 reporter secretly filmed him exposing some of the company's questionable practices.
