Here's why Donald Trump should be very concerned about the huge cache of data the FBI seized from Roger Stone

A national security expert outlined why Donald Trump should be worried that special counsel Robert Mueller now has access to "terabytes" of data from Roger Stone that was seized in his FBI raid earlier this week.

"We often talk details about the Mueller investigation that should make Donald Trump worry," independent journalist Marcy Wheeler wrote Thursday. "And I think the government’s motion to declare Roger Stone’s prosecution a complex case ought to do that."

In the Mueller filing, Wheeler noted, investigators claimed they have "terabytes of electronic records and data" — including information that may not be pertinent to the immediate case against Stone but "but might look more interesting given the hints of campaign finance violations in this investigation."

While there are indications that the special counsel already possessed Stone's "multiple cell phones, computers, and hard drives, his iCloud and email accounts, and the aforementioned financial records," the filing indicates that Mueller's team also got access to new devices in the raid.

"For most of the year during which prosecutors have been obtaining testimony from Stone’s associates, one by one, they’ve been sitting on a mountain of evidence, and evidence not relating exclusively to the obstruction charges against Stone," Wheeler wrote. "This designation as a complex case will give Stone some time to think about that."