Former Trump campaign manager Paul Manafort and his onetime business partner and protege Rick Gates will be told to surrender to federal authorities on Monday as the first charges from the probe of possible Russian meddling in the 2016 U.S. presidential election are unsealed.

The move represents a dramatic turn in special counsel Robert Mueller’s investigation.

The New York Times reported that Manafort and Gates will be taken into custody. Manafort was seen leaving his home at 8:00 a.m. with his attorney.

A federal grand jury approved the indictments on Friday and a judge ordered them sealed.

Manafort and Gates were the one-two punch responsible for keeping Republican National Convention delegates in line last year as the possibility emerged of a contentious floor fight over the presidential nomination.

Manafort was fired shortly after the convention, to be replaced by pollster Kellyanne Conway.

That move came after reports that Manafort pocketed at least $12 million in undisclosed payments from Viktor Yanukovych, the pro-Russia former Ukrainian president.

Manafort and his firm, which Gates helped run, spent years as Yanukovych’s political consultants.

Mueller’s probe has reportedly focused on wire transfers Manafort made from Ukraine to private accounts and whether he paid taxes on that income.

The Wall Street Journal reported Monday that at least one charge leveled against Manafort is federal tax fraud.

The Russia investigation has cast a shadow over President Donald Trump’s nine-month-old presidency and widened the partisan rift between Republicans and Democrats.

U.S. intelligence agencies concluded in January that Russia interfered in the election to try to help Trump defeat Democrat Hillary Clinton by hacking and releasing embarrassing emails and disseminating propaganda via social media to discredit her.

Mueller is also investigating whether Trump campaign officials colluded with those Russian efforts.

Trump tweeted Monday morning about a report that Barack Obama’s campaign organization funneled nearly $1 million to the law firm that served as a pass-through last year between Democrats and an opposition research firm that produced the salacious and discredited ‘dirty dossier’ on the president.

‘Report out that Obama Campaign paid $972,000 to Fusion GPS. The firm also got $12,400,000 (really?) from DNC. Nobody knows who OK’d!’ the president tweeted on Monday.

That tweet came a half-hour before news broke that Manafort and Gates had been indicted. The White House hasn’t yet commented on their surrender.

Trump has denied the allegations of collusion with the Russians and called the probe ‘a witch hunt.’ The Kremlin also has denied the allegations.

Mueller, a former director of the Federal Bureau of Investigation, has been looking into possible links between Trump aides and foreign governments, as well as potential money laundering, tax evasion and other financial crimes, according to sources familiar with the probe. He also is exploring whether Trump or his aides have tried to obstruct the investigation.

Mueller was appointed to lead the investigation a week after Trump’s May 9 firing of FBI Director James Comey, who was heading a federal probe into possible collusion with Russia.

Trump initially said he fired Comey because his leadership of the FBI was inadequate.

In a later interview with NBC, he cited ‘this Russia thing’ as his reason.

On Sunday, Trump tried to shift the focus back to Democrats and Clinton, tweeting that the Russia issue was being used to sidetrack the Republican push for tax reform and praising Republican ‘anger and unity’ on the need to look into whether Democrats and the Clinton campaign paid for a portion of a dossier that detailed accusations about Trump’s ties to Russia.

Special White House counsel Ty Cobb said the president’s tweets were ‘unrelated to the activities of the Special Counsel, with whom he continues to cooperate.’

Investigators led by Mueller have interviewed former White House chief of staff Reince Priebus, former spokesman Sean Spicer and other current and former White House and campaign officials.

In July, FBI agents raided Manafort’s Virginia home; his financial and real estate dealings and prior work for a pro-Russian political party in Ukraine have been a focis of Mueller’s team.

Mueller also has investigated Michael Flynn, an adviser to Trump’s campaign and later his national security adviser. Flynn was fired from that post in February after misleading Vice President Mike Pence about the extent of his conversations with Russian Ambassador Sergei Kislyak last year.

The indictment in Mueller’s probe was first reported by CNN, which said the target could be taken into custody on Monday.

That possibility spurred some of Trump’s conservative allies to call for Mueller’s firing. Sebastian Gorka, an outspoken former adviser who left the White House in August, said on Twitter that Mueller ‘should be stripped of his authority’ and investigated if he executed warrants in the probe.

The White House said in the summer that Trump had no intention of firing Mueller even though he questioned his impartiality.