photo - President Donald Trump speaks during a news conference with Colombian President Juan Manuel Santos in the East Room of the White House in Washington, Thursday, May 18, 2017. (AP Photo/Susan Walsh)
President Donald Trump speaks during a news conference with Colombian President Juan Manuel Santos in the East Room of the White House in Washington, Thursday, May 18, 2017. (AP Photo/Susan Walsh) 

The law enforcement investigation into possible coordination between Russia and the Trump campaign has identified a current White House official as a significant person of interest, showing that the probe is reaching into the highest levels of government, according to people familiar with the matter.

The senior White House adviser under scrutiny by investigators is someone close to the president, according to these people, who would not further identify the official.

The revelation comes as the investigation appears to be entering a more overtly active phase, with investigators shifting from work that has remained largely hidden from the public to conducting interviews and using a grand jury to issue subpoenas. The intensity of the probe is expected to accelerate in the coming weeks, the people said.

The sources emphasized that investigators remain keenly interested in people who previously wielded influence in the Trump campaign and administration but are no longer part of it, including former national security adviser Michael Flynn and former campaign chairman Paul Manafort.

Flynn resigned in February after disclosures that he had lied to administration officials about his contacts with Russian Ambassador Sergey Kislyak. Current administration officials who have acknowledged contacts with Russian officials include President Trump’s son-in-law, Jared Kushner, as well as Attorney General Jeff Sessions and Secretary of State Rex Tillerson.