Special counsel Robert Mueller has subpoenaed a former employee of data firm Cambridge Analytica, a spokesperson for the employee told The Guardian.
The ex-employee, Brittany Kaiser, is cooperating fully with Mueller's investigation into Russian interference in the 2016 election, the spokesperson added. Kaiser is also cooperating with congressional and other legal investigations into the actions of Cambridge Analytica.
Cambridge Analytica shut down last year after becoming embroiled in controversy for improperly obtaining data on tens of millions of Facebook users.