The FBI inquiry into sexual assault allegations against Supreme Court nominee Brett Kavanaugh has resulted in the questioning of his friends, as well as a friend of his accuser, Christine Blasey Ford. The bureau, however, did not interview Kavanaugh or Ford.

That has raised questions from lawmakers and prosecutors like Fran Townsend, who was homeland security adviser to President George W. Bush and served on his administration with Kavanaugh.

"I personally don't believe as a prosecutor that you could have a credible and complete investigation without an interview of Dr. Ford," Townsend said Thursday on "CBS This Morning."

Townsend, a CBS News senior national security analyst, was one of 84 women who signed a letter supporting Kavanaugh's nomination before the allegations surfaced publicly.

She said the limited scope of the FBI inquiry hurts the agency's credibility.

"Everybody called for this because they were an independent third party. They were the gold standard in terms of an investigation, non-partisan. And to have them now say we found no support for Dr. Ford's allegations, but we didn't speak to her, I think does undermine their credibility," she said.

While both Ford and Kavanaugh testified before the Senate Judiciary Committee last Thursday, Townsend said there was information the FBI would not get without questioning Ford.

"You don't get out of that the therapist notes, which you could have asked her for permission to get. You don't get the polygraph or the polygraph report, which you could have asked her for. And so there are a lot of good reasons in a thorough investigation, as a prosecutor, I think I would have sent the agents back out to do that," Townsend said.

The FBI submitted their findings to the Senate before its one-week deadline to conduct the review. Lawmakers are reviewing a single copy of the documents in a secure room in the basement of the Capitol. The Senate vote to confirm Kavanaugh is expected to take place Saturday.

"The real question here … is what [do] Sens. Flake, Collins and Murkowski think of this? Do they think it's adequate? And frankly, I don't think you've done very much to give them much political cover because it's not been that widespread. So, today we want to watch those three," Townsend said.