From USA Today:

But Paul Rosenzweig, a former senior counsel with Ken Starr’s independent counsel investigation of President Bill Clinton and now a senior fellow at the R Street Institute, said it’s not yet clear whether Mueller could win additional cases without Manafort.

“It may be saying he has enough information to be sure that Manafort is lying to him and can’t in good faith use him for whatever else he’s looking for,” he said.

Rosenzweig said the interesting question is about where Manafort was being false. A report Tuesday in The Guardian, a British newspaper, said Manafort had met with Julian Assange, founder of WikiLeaks, which distributed Clinton’s campaign emails before the election. Mueller already has charged Russian military intelligence officers with hacking Democratic computers to get the emails.

“If true, that would be the missing link between the campaign and Russia,” Rosenzweig said.

…But Rosenzweig said he thought the Trump Tower meeting could have been a one-time event and not the crux of the investigation.

“I’m guessing it’s other stuff,” he said. “I’m guessing it’s something bigger.”