‘He’s sunk’: Michael Wolff says White House aides terrified of Mueller looking at Trump’s finances

The investigation into Russian collusion with President Donald Trump's campaign might end up taking out the president and his family due to possibly illegal financial activities, according to biographer Michael Wolff.

In an interview with CNBC's "Squawk Box," Wolff said that Trump's own staff and officials don't think that he colluded with Russia, but they're concerned about whether special counsel Robert Mueller will look into Trump's business dealings and investments.

"People don't think in the White House — don't think that he colluded with Russia. … They do think that if the investigation goes near his finances, he's sunk. Everybody, again, to a man," Wolff said in a "Squawk Box" interview.

Mueller has begun the process of reaching out to the president's attorneys and . The move is something his lawyers were attempting to avoid entirely.

Trump has repeated over and over again that there "was no collusion," but financial records could reveal a different story. The president has been cooperating with the Mueller investigation, but he said that if the special counsel looked into his finances that it would "cross a red line."

For those criticizing Wolff's book, the author explained that he is confident of the book's accuracy. The recordings he said that he compiled will back up the quotes.

"People who are denying they spoke to me, I do have them on tape, but I made a deal with them there," he said.

Watch the interview below:

If Russia probe goes near Trump's finances, 'he's sunk,' 'Fire and Fury' author Michael Wolff says from CNBC.