Kurt Olsen, who joined the Justice Department this spring after working at the White House, decided to leave the Florida-based investigation, the two sources said. A third source said Olsen is still working for the Justice Department.
Olsen's departure comes a little more than two weeks after the DOJ official who had been overseeing the investigation, Joseph diGenova, resigned after clashing with Justice Department leadership. One of the sources said Olsen had grown disillusioned with the state of the investigation after diGenova's resignation.
The investigation, which is being run by the US Attorney's Office in Miami, is seeking to establish that Trump was the victim of a criminal conspiracy by former federal law enforcement and intelligence officials.
It is examining both the US intelligence assessment that Russia sought to aid Republican Trump's 2016 presidential campaign and a later investigation into classified documents stashed at Trump's Mar-a-Lago resort following his first term.
Olsen led a call earlier this month with lawyers for former CIA Director John Brennan, who served under former Democratic President Barack Obama, and has been informed he is a target of the investigation, according to court documents.
Olsen as a private lawyer helped push Trump's false claims of widespread voter fraud in the 2020 election. He joined the Justice Department following a stint as a White House election security official, where he pursued debunked claims that voting machines were rigged against Trump.