Nick Ackerman, a former Watergate prosecutor, said Saturday that the big issue in special counsel Robert Mueller's investigation is not whether the Trump campaign coordinated with Russia, but whether it conspired to steal emails from prominent figures in the Democratic Party.

"I think the big enchilada here is the conspiracy to break into the Democratic National Committee [DNC] in violation of the federal computer crime law and to use those emails to help Donald Trump get elected," Ackerman said on MSNBC.

"All of that is motive as to why Donald Trump and others were endeavoring to obstruct the investigation, and why Donald Trump told [former FBI Director] James Comey to let the investigation on [former national security adviser Michael] Flynn go," he added. "All of this is going to come together in 2018."

Mueller and his team are investigating Russia's role in the 2016 presidential election, as well as possible collusion between the Trump campaign and Moscow.

The U.S. intelligence community assessed last year that Russia was behind a cyber breach at the DNC that resulted in embarrassing and damaging emails being leaked to the public.

Trump and his associates have repeatedly denied allegations that the campaign sought to conspire with Russia to disrupt and influence the election, and have insisted that Mueller's investigation is a "witch hunt."

Collusion itself is not a federal crime, except in antitrust matters. Mueller has not brought charges against Trump or any current White House staffer, though Flynn pleaded guilty earlier this month to lying to FBI agents about his contacts with Russia's ambassador to the U.S. in the month before Trump took office.

Flynn departed the White House in February after it was revealed that he had lied to Vice President Pence and others about his contacts with the ambassador, Sergey Kislyak. Comey, who was fired by Trump in May, later testified before a congressional panel that the president once asked him to drop the FBI's investigation into Flynn.

The Russia investigation has cast a shadow over Trump's first year in office, and despite claims from the president's lawyers that it will soon come to an end, news reports indicate that it could continue well into 2018.

- Updated at 9:47 p.m.