WASHINGTON — For more than two years, President Trump has repeatedly attacked the Russia investigation, portraying it as a hoax and illegal even months after the special counsel closed it. Now, Mr. Trump’s own Justice Department has opened a criminal investigation into how it all began.

Justice Department officials have shifted an administrative review of the Russia investigation closely overseen by Attorney General William P. Barr to a criminal inquiry, according to two people familiar with the matter. The move gives the prosecutor running it, John H. Durham, the power to subpoena for witness testimony and documents, to impanel a grand jury and to file criminal charges.