CNN said the exact nature of the charges wasn’t immediately clear because the court documents had not yet been made public.

Hunter Biden in October pleaded not guilty to charges that he lied about his drug use while buying a handgun, in the first criminal prosecution of a sitting US president’s child.

Special counsel David Weiss brought those charges against Hunter Biden after an earlier proposed plea deal unraveled under questioning from a judge. Weiss is still investigating whether the younger Biden can be charged for tax law violations.

The special counsel investigating Hunter has employed a grand jury in Los Angeles to seek documents and possible testimony from multiple witnesses as part of the federal investigation of Hunter Biden’s business dealings, CNN reported last month.