Legal experts have warned that Donald Trump could be headed to prison as Robert Mueller’s Russia probe has now expanded to include a grand jury that can dig much deeper into Trump’s finances and other aspects of his personal life.

On Thursday, the Wall Street Journal published a report claiming that Mueller, the special counsel selected to oversee the Russia investigation after Trump fired FBI Director James Comey, is moving steadily forward and has impaneled a grand jury. The newspaper noted that the move means the investigation could stretch on for months.

The inclusion of a grand jury also means the investigation has spread beyond former National Security Adviser Michael Flynn, CNBC noted. Mueller believes he will need to subpoena records and take testimony from witnesses, the original Wall Street Journal report noted.

While this does not necessarily mean that Mueller will level criminal charges against Donald Trump, experts note that it has significantly raised the possibility that the president could be charged and ultimately face prison time. There has already been significant chatter that Trump could face charges for his involvement in covering up Donald Trump Jr.’s meeting with a Kremlin-backed lawyer offering dirt on Hillary Clinton that had been stolen by the Russian government.

A report from The Washington Post claimed that President Trump “personally dictated” a statement to his son that the meeting “primarily discussed a program about the adoption of Russian children.” But it was later revealed that the basis of the meeting was to share dirt on Hillary Clinton.

Breaking news: In apparent sign of Mueller's Trump-Russia probe ramping up, special counsel impanels grand jury https://t.co/GBd350EtS6 — The Globe and Mail (@globeandmail) August 3, 2017

Richard Painter, the former chief White House ethics lawyer under George W. Bush, told Salon that Trump’s actions could give Robert Mueller the opening to bring criminal charges against the president.

“He is already in hot water for that because of the [former FBI director James] Comey firing and his admission that it was about Russia.”

“A misleading statement, even a lie, told to the press or to the public is not itself a crime,” Painter said. “But he must have known that his son and others would be called to give evidence in the criminal proceedings. Once he drafts a public statement that he knows is false, he is boxing them in when they talk to [special prosecutor Robert] Mueller, testify before Congress and at trial, or at least he is attempting to do so. That is obstruction of justice, witness tampering.”

BREAKING: Robert Mueller's investigation is following the Trump-Russia money trail, sources tell CNN https://t.co/s7A3CjIVdk pic.twitter.com/HOxnZjLFk3 — CNN Politics (@CNNPolitics) August 3, 2017

It was not clear from Thursday’s report if Robert Mueller’s grand jury will be looking into Donald Trump’s work with his son to craft what Painter called a “misleading statement” regarding the 2016 meeting. CNN has already reported that the grand jury will be looking largely into financial ties between Trump and Russia. There is also plenty of disagreement over whether Trump himself actually could end up in prison, with a debate among legal scholars whether the president can be criminally charged or if he could pardon himself.

[Featured Image by Spencer Platt/Getty Images]