Federal prosecutors in Delaware are investigating President-elect Joe Biden s son Hunter Biden over tax issues, the transition team announced Wednesday.

News of the investigation comes just as Joe Biden is set to announce his nominee for attorney general of the United States. Hunter Biden had been a constant target for President Donald Trump during the 2020 campaign.

Hunter Biden said in a statement that the U.S. Attorneys Office in Delaware informed his legal counsel about the investigation on Tuesday. The U.S. Attorneys Office declined to comment, citing Justice Department policy.

I take this matter very seriously but I am confident that a professional and objective review of these matters will demonstrate that I handled my affairs legally and appropriately, including with the benefit of professional tax advisors, Hunter Biden said.

Joe Biden is deeply proud of his son, who has fought through difficult challenges, including the vicious personal attacks of recent months , only to emerge stronger, a statement from the transition team said.

A CNN reporter was working on a story about the investigation and had been in contact with Hunter Bidens legal counsel when the transition team for Joe Biden and Vice President-elect Kamala Harris sent out its press release. The reporter, senior justice correspondent Evan Perez, reported that the investigation began in 2018, but was put on hold ahead of the 2020 election under DOJ policy.