(CNN) A Democratic member of the House Intelligence Committee says that, in light of new developments, key figures in the Russia investigation, including Donald Trump Jr., should be subpoenaed to testify again.

"I think that Mr. Cohen, Trump Jr. and others need to come back in light of new documents, new revelations, new issues that have become aware to the public. They should come back under subpoena and be forced to answer questions," Rep. Mike Quigley told David Axelrod on "The Axe Files," a podcast from the University of Chicago Institute of Politics and CNN.

Quigley told Axelrod that he believes that many of those who testified before his committee had been signaled by Trump to stay loyal in exchange for a pardon.

"Many of them refused to answer the questions because they just didn't feel like they had to," the Illinois Democrat claimed.