Don't miss the powerful "Fox News Reporting" special, anchored by Bret Baier, that follows the Clinton money trail. Tune in to "The Tangled Clinton Web," Friday night at 10p ET on Fox News Channel.

Charles Krauthammer weighed in on "The O'Reilly Factor" tonight about the Clinton Foundation controversy.

In a soon-to-be-released book called "Clinton Cash," author Peter Schweizer alleges that while serving as secretary of state, Hillary Clinton did favors for foreign governments and groups in exchange for cash.

Krauthammer said that this controversy is less about the legal corruption of the Clintons and more about their moral corruption, since the allegations against Clinton will be difficult to prove or prosecute.

"It's big and it's bad, but there's one problem for those of us who are concerned about it," Krauthammer said. "She burned the tapes, she eliminated the emails."

"There may not be enough evidence or explicit evidence of a criminal quid pro quo, but this is simply shady."

Krauthammer said that the only way to uncover hard evidence may be to access the deleted emails on Clinton's private servers. In the absence of that, it will be difficult to charge her with anything.

"The Clintons are clever. They cover their tracks," Krauthammer said.

Get more insight from Krauthammer in the clip above and don't miss "The Tangled Clinton Web," Friday night at 10p ET on Fox News Channel.

You Might Also Like ...

Henry: Hillary Pushing Back on 'Clinton Cash' Using Old 'Right-Wing Conspiracy' Playbook

O'Reilly: Big Question in 2016 Race Is if Hillary Will Push Obama's Taxes

O'Reilly: Hillary's Campaign is 'Fodder for Pundits and Comedians'

Judge Nap on 'Clinton Cash': Menendez Was Indicted for Lesser 'Quid Pro Quo' Allegations