Hillary Clinton should have been "deeply aware" that she was mishandling classified information, a House Republican said on Monday, adding that he was optimistic law enforcement would soon conclude its massive investigation into the matter.

"It is hard for me to imagine how a professional who had classification authority at the State Department, someone very well-versed in the proper handling of information and the requirements of what was permissible, could possess that much information on a non-secured device or system without being deeply aware the information was there," Rep. Mike Pompeo, R-Kan., told the Washington Examiner

To date, the State Department has released 1,340 emails Clinton stored on a private server that have been marked as classified. In defense, Clinton has said they were not marked as such. Pompeo, a member of of the House Select Committee on Intelligence, called that defense "irrelevant."

"It's not the word 'secret' that makes the document secret. It's that the information is secret," he said. "It is possible to read a document and not know whether it is classified or not. I've seen things where I've said, 'I wonder if that needed to be classified.' Often it's the case that I'm reading a classified document and I think, why aren't I reading this in a secured facility where it's marked as secret?"

"It's possible there are close calls, but we're now over … 1,300 emails that were deemed at the confidential level. Someone who has spent a lot of time staring at classified information ought to have known the information was classified," he added.

Reports made public early on Monday indicated that the Federal Bureau of Investigation had expanded its probe into Clinton's mishandling of classified information to look at charges of public corruption related to the nonprofit Clinton Foundation.

That investigation has grown to involve as many as 150 FBI agents, former U.S. attorney Joseph DiGenova told the Examiner. Yet as of Monday afternoon, Pompeo had yet to be briefed on the latest allegations, in spite of his position on both the Intelligence Committee and the Select Committee on Benghazi.

"The mounting evidence that there was classified information on the former secretary of state's server is overwhelming," Pompeo said. "I'm hopeful the FBI will quickly make its determination and share it with the American people, whatever it may be."

"If they conclude my assumptions are wrong, so be it," he added. "But they ought to let us all know so we can move on, so we won't have to be guessing or speculating. Americans deserve to get the answer."