Federal prosecutor Maria Medetis Long has been removed from her role leading a criminal investigation into former CIA Director John Brennan, according to sources familiar with the matter.

Long, who serves as chief of the national security division in the U.S. attorney's office for the southern district of Florida, had been overseeing the investigation into whether Brennan lied to Congress. The prosecutor informed attorneys involved in the case that she was no longer handling it, CNN first reported.

According to sources, Long had expressed reservations about the case and raised concerns about whether the evidence justified moving forward with a bid to prosecute Brennan. The career Justice Department lawyer reportedly had doubts about the strength of the case against the former CIA director.

The investigation centers on allegations that Brennan provided false testimony to Congress. Brennan led the CIA during the Obama administration and oversaw the agency when it concluded that Russia interfered in the 2016 election to boost Donald Trump's candidacy.

Long is a career attorney with extensive experience in national security matters. Her removal from the case comes amid ongoing scrutiny of investigations launched during the Trump administration targeting former intelligence officials.

The Department of Justice has not responded to requests for comment regarding Long's departure from the case or the current status of the investigation into Brennan.