Special counsel Robert Mueller "absolutely" has President Donald Trump's tax returns, former U.S. Attorney Chuck Rosenberg said Thursday.

In remarks on MSNBC's "Deadline: White House," Rosenberg declared, "One of the first thing prosecutors get is tax returns."

Pressed on whether he thought Mueller already has Trump's tax returns, Rosenberg quickly replied: "Absolutely, no question in my mind, from day one."

"The first thing that white collar prosecutors do . . . is you get tax returns and you get credit reports," he said, adding "it's easy to do."

"You get tax returns with an order from a federal judge – you get credit reports with a grand jury subpoena – because those are the documents that give you leads," he said.

"They tell you where the money is coming from. They tell you where the money is going, and they tell you who to talk to get more leads. So, does Mueller have Trump's tax returns? You bet."

Trump has refused to release his tax returns during the 2016 presidential campaign, a stance he has maintained at the White House.

Trump was the first president candidate since Richard Nixon to refuse to release his tax returns.