CNN reported Friday night that a federal grand jury has reportedly approved the first charges in Mueller's probe. We don't know yet who has been charged or what the charges are; the outlet says they're sealed under an order from a federal judge. However, CNN's source said that whoever the charges are against may be taken into custody as soon as Monday.
Peter Carr, a spokesman in the special counsel's office, declined to comment. By June, Trump himself was reportedly under investigation for obstruction of justice.
Sources familiar with Mueller's investigation said he has used that broad authority to investigate links between Trump aides and foreign governments as well as possible money laundering, tax evasion and other financial crimes. Other incidents that have come up in the investigation are meetings between former Russian Ambassador to the US Sergey Kislyak with Trump's son-in-law and adviser Jared Kushner and former National Security Adviser Michael Flynn.
The Kremlin has also denied the claims.
After breaking the news of the charges, and with limited information, CNN commentators, journalists and legal experts went on to speculate about who might be charged, and what the charges might be.
Mueller was appointed as the special counsel in May.
Michael Flynn, who briefly served as Mr Trump's national security adviser before he was sacked in February for misleading vice president Mike Pence about the extent of his conversations with a Russian ambassador, is also under investigation. NBC News later confirmed reports of a Monday indictment.
Lawyers involved in the Mueller probe where spotted entering the DC federal court room where the grand jury met to hear testimony in the investigation, according to the report, but no announcement was made about charges.