Former national security adviser John Bolton is expected to face federal charges soon over alleged mishandling of classified materials, according to two federal officials.

The U.S. attorney’s office in Maryland is reportedly preparing the indictment, following FBI searches of Bolton’s home and D.C. office in August as part of a national security investigation.

The searches were prompted by CIA intelligence and focused on possible violations of the Espionage Act related to the possession and sharing of defense information.

Bolton’s attorney, Abbe Lowell, denied wrongdoing, saying all materials were legally reviewed and cleared years earlier for Bolton’s memoir., NBC News has reported.

The case revives long-standing tensions between Bolton and President Trump, who has publicly called for Bolton’s prosecution.