Aaron Zebley testifying will ‘establish the precedence’ Congress can interview all Mueller investigators: Democrat
Rep. Peter Welch (D-VT) on MSNBC (screengrab)

The House Permanent Select Committee on Intelligence will swear in deputy special counsel Aaron Zebley along with special counsel Robert Mueller, MSNBC's Rachel Maddow reported Tuesday.

MSNBC's Lawrence O'Donnell followed up on Maddow's reporting while interviewing Rep. Peter Welch, who sits on the Intelligence Committee.

"In your committee tomorrow, Aaron Zebley’s going to be a sworn witness at this stage. Do you expect committee members to solicit testimony from him as well as Robert Mueller? As much as Robert Mueller?" O'Donnell asked.

"Our focus is going to definitely be on Mueller," Welch replied. "And our goal is to let Mueller speak because if he just describes what is in the report, that’s very, very damaging to the president."

"Also, we’re establishing the precedent that we’ve been fighting for, that some of these investigators, we have a right to call them, to inquire what's going on," Welch explained. "Mueller is at the top, but a lot of the people doing the details, where they know what the negotiations were, they know what happened, they’re relevant to get the story out to the American people."

"We’re glad that he’s going to be there and we are glad that he’s going to be sworn in," he added.

Former Richard Nixon White House counsel John Dean has also said he thinks Zebley's testimony will be key.