'If you lie you're a felon -- if you're president you're impeached': Morning Joe warns of grand jury perils
Mika Brzezinski and Joe Scarborough (MSNBC)

MSNBC's Joe Scarborough showed how reports that Robert Mueller had impaneled a federal grand jury to examine Trump campaign ties to Russia had effectively made the special counsel untouchable.

The grand jury has issued subpoenas related to the June 2016 meeting between the president's son and two other top campaign officials and a Russian lawyer, and Mueller has reportedly expanded the probe to include potential financial crimes unrelated to the election.

"Now that there is a grand jury impaneled, firing him is simply untenable," Scarborough said.

A grand jury in Virginia has already been investigating former national security adviser Mike Flynn for several months, but this new panel in Washington will examine Trump, his family and his associates and their financial and political ties to Russia.

"This could also be signaling that whatever they're looking at has a nexus in D.C., not out in Virginia, so I think that's important," said former FBI agent Clint Watts, "and I think it also signals strategy. You want to bring out in testimony or records things you want to lock down early, and this can really signal the direction they're trying to go."

Watts also pointed out that testimony under oath boxed in both witnesses and other targets in the investigation, and Scarborough issued a warning to Trump and his associates.

"If you lie in front of a grand jury you’re a felon — and you’re going to go to jail," Scarborough said. "If you’re president, you’re going to be impeached."