Earlier this week, the chairman of the Senate Intelligence Committee — North Carolina Republican Richard Burr —said they have not found direct evidence of collusion between the president's 2016 campaign and Russia. The committee's ranking Democratic member, Mark Warner of Virginia, disagreed with Burr's assessment but did not offer his own, according to NBC News.

Homeland security expert Juliette Kayyem says that doesn't tell the whole story. Kayyem is on the facultyof Harvard’s Kennedy School, a CNN analyst, and CEO of ZEMCAR.

"This idea of the direct collusion aspect I think we all have to get out of our head," Kayyem said on Boston Public Radio Wednesday.

"Everyone is looking for a smoking gun. Do we have the phone call between Putin and Trump that says, 'We're going to do this?' I don't think that thing exists," she continued.

Kayyem believes the investigation being led by Special Counsel Robert Mueller is instead putting together a more nuanced story about President Donald Trump's relationship with Russia.

"I think what Mueller is doing is finding all these different pieces of evidence that lead to a narrative that the president was mightily compromised by the Russians for a variety of reasons: financial, personal, the tapes, whatever it is, and that there were contacts between the Trump campaign and the Russians," she explained.

That's a different approach than the Senate committee's, she says.

"The Senate is not looking at the same things Mueller is," Kayyem said.