The investigation concerns that Jack Smith is alleged to have engaged in alleged "illegal political activity".
The independent federal agency Office of Special Counsel confirmed on Saturday that the investigation against Jack Smith has been initiated.
Smith has previously – after being appointed by then Minister of Justice Merrick Garland in November 2022 – investigated whether and if so how Donald Trump tried to cling to power during his first term of office since Democrat Joe Biden won the presidential election in 2020.
Two investigations against Trump
Smith led two federal investigations against Trump, one linked to the storming of the congressional building Capitolium and one about Trump's handling of classified documents in Mar-a-Lago in Florida, after he left the White House.
Both investigations were closed before they went to trial since Trump won the presidential election in November last year because he would in any case enjoy immunity as president.
Smith then left his position within the Ministry of Justice in January this year before Trump, who had promised to fire him, took office as president.
Support Biden
Trump and his Republican allies – including Senator Tom Cotton from Arkansas – have since then, without presenting any evidence, accused Smith of having violated the ban on certain public officials engaging in political activity.
On Wednesday, Tom Cotton requested that the Office of Special Counsel investigate Smith, motivated by the fact that he acted as he did to support Joe Biden and his then Vice President Kamala Harris.