Federal prosecutors in Florida have begun targeting former key intelligence officials as part of a Justice Department investigation into Russian interference in Donald Trump’s 2016 campaign, sources told CNN.

Former CIA Director John Brennan and former Director of National Intelligence James Clapper are among those expected to receive subpoenas, along with ex-FBI officials Lisa Page and Peter Strzok, reports say.

CNN’s Katelyn Polantz told Erin Burnett Friday night that the new action from Trump’s Department of Justice “is not done yet” and that “dozens of subpoenas” are going out to officials connected to the 2017 intelligence community assessment that summarized Russian efforts to interfere in the election and the Trump campaign’s contacts. Investigators are demanding documents from July 2016 to February 2017, including emails, texts and computer files, the network reported.

But, as Polantz noted: “There's some real head scratchers around this right now.”

“First of all, what they're asking for are very old records, federal criminal cases only usually are charged in a five-year window. This is stuff from almost 10 years ago,” she said.

The subpoenas were sent out from the U.S. Attorney’s Office in the Southern District of Florida, which has jurisdiction over Mar-a-Lago. While CNN added that while the link between this probe and the original FBI investigation, known as “Crossfire Hurricane,” is not fully clear, Trump allies have argued the Justice Department can revisit the earlier probe as part of broader inquiries into Trump’s campaign, transition and subsequent actions, including the classified documents investigation.

The effort marks the latest chapter in nearly a decade of legal scrutiny surrounding Trump’s 2016 campaign.