The FBI said last year it did not find evidence of a conspiracy behind the events of Jan. 6, 2021, at the U.S. Capitol, according to insiders.

And now, after intensive investigation by the partisan House select committee, Democrats who assert that then-President Trump conspired to "overturn the election" and maintain power by creating a riot so far have come up short, according to a Democratic senator.

On Sunday, ABC News veteran political reporter Martha Raddatz, guest hosting "This Week," asked Sen. Heidi Heitkamp, D-N.D., about possible criminal charges stemming from the Jan. 6 probe and the issues "that still need to be investigated."

"I think there needs to be more nexus, what we call nexus between the president and the insurrectionists," she said in an exchange spotlighted by reporter Paul Sperry on Twitter.

Heitkamp emphasized: "I don't think they have the nexus yet."

The Jan. 6 committee is claiming the Proud Boys group was part of a grand conspiracy directed by Trump. However, the New York Times reported last September that a member of the Proud Boys who entered the Capitol on Jan. 6 was an FBI informant. And, significantly, the paper reported that the informant – who texted his bureau handler during the riot – insisted the Proud Boys had no advanced plan to enter the Capitol and disrupt the certification of the 2020 presidential election.