A Washington, D.C., federal grand jury on Friday approved the initial charges stemming from the investigation led by special counsel Robert S. Mueller III, CNN reported.

The charges remain sealed by a federal judge, according to CNN. It remains unknown what those charges are but individuals could be taken into custody as soon as Monday, the network said.

The Justice Department in May appointed former Mueller, a former FBI director, as a special counsel for the investigation into possible ties between President Donald Trump’s campaign and Russian operatives, and Russian interference into the 2016 presidential election.

Deputy Attorney General Ron Rosenstein signed the order appointing Mueller shortly after Trump abruptly fired FBI Director James B. Comey.

Both Republicans and Democrats met Mueller’s appointment with praise at the time.