'Follow the money': CNN's Jeffrey Toobin explains the significance of Trump CFO's immunity deal
Trump Organization CFO Allen Weisselberg/Screenshot

On Friday, federal prosecutors announced that they are granting immunity to Allen Weisselberg, President Trump’s longtime financial advisor, in exchange for testimony in the criminal probe of Michael Cohen.

Weisselberg is heard on tape discussing hush-money payments to women alleging they'd had affairs with Donald Trump ahead of the election.

On CNN Tuesday, legal analyst Jeffrey Toobin pointed out that as the chief money guy, Weisselberg can offer important information to prosecutors.

"He knows where the money is," Toobin said. "One of the oldest rules of law enforcement is follow the money and CFOs are often very, very important witnesses."

"They know where the money comes in and where it comes out and the fact that he has now been granted immunity is enormously significant because it means investigators now have basically a complete window into the financial operations of the Trump organization," Toobin added.

That means that allegations of financial fraud or campaign finance violations will be easily confirmed if they're true.

"If there is something improper, the feds are very likely going to know about it."