Special counsel Robert Mueller's inspectors are subjecting President Donald Trump to a "legal colonoscopy" with their intense investigation of his business practices, Harvard Law professor emeritus Alan Dershowitz said Tuesday.
"What we don't know is whether there's an investigation dealing with the business affairs prior to becoming a candidate, prior to becoming president," Dershowitz told Fox News' "America's Newsroom" co-host Sandra Smith.
"Nobody knows. And he has been subjected to what I call a legal colonoscopy. They're looking at every conceivable aspect of his business life. Who knows how many people can survive that kind of an inquiry?"
Dershowitz added that as far as is known at this point, Trump isn't vulnerable to being prosecuted for obstruction of justice, "on constitutional grounds, and that seems to be clear. There [also] doesn't seem to be evidence of any illegal collaboration between Russia and the Trump campaign."
Meanwhile, Trump has said he has no intention of firing Mueller, but Democrats are "fueling the speculation" that he will, said Dershowitz.
"I can't see a feasible reason why the president would consider firing Mueller," Dershowitz told Smith. "That would create a real problem on the Republican side of the aisle. I don't think he'll fire him or should fire him."
Dershowitz said he also thinks Trump is "100 percent" right when he calls Mueller's investigation the "ultimate witch hunt" and says it should never have begun in the first place.
"There never should have been an appointment of special counsel and there was no probable cause that crimes were committed," said Dershowitz. "I've seen no credible evidence that crimes were committed by the president. As I said from day one, there should have been a special investigative commission, non-partisan with subpoena power to do something about preventing meddling in elections in the future, instead of going behind the closed doors of a grand jury."
Trump is "playing good cop, bad cop," he added. "He has some lawyers cooperating and some attacking Mueller because he wants to be ready to attack in the event there are recommendations that are negative to the president."
Meanwhile, it would be the "worst approach" for Trump to appear before a grand jury without an attorney.
"If he can have several hours with restricted subjects with his lawyer present and an opportunity to confer with his lawyer it may be the least worst solution but may not be an alternative available to him," said Dershowitz.