The FBI is searching the Maryland home and Washington office of John Bolton, who served in President Donald Trump’s first administration as national security adviser, as part of an investigation into the handling of classified information, a person familiar with the matter said Friday.

Bolton emerged as an outspoken critic of Trump after being fired in 2019 and feuded with the first Trump administration over a scathing book he wrote documenting his time in the White House.

He was not in custody Friday and has not been charged with any crimes, said the person, who was not authorized to discuss the investigation by name and spoke to The Associated Press on the condition of anonymity.

The searches, seemingly the most significant public step the Justice Department has taken against a perceived enemy of the president, are likely to elicit fresh alarm that the Trump administration is using its law enforcement powers to go after his foes.

The searches of Bolton’s home and office come as the Trump administration has taken steps to examine the activities of other critics, including by authorizing a grand jury investigation into the origins of the Trump-Russia probe that dogged Trump for much of his first term.