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Sen. Susan Collins today said it is "absolutely imperative" that David Petraeus should still testify on the attack in Benghazi despite his resignation as CIA director due to his affair.

"There are so many unanswered questions at this point," Collins, R-Maine, said outside her office this morning. "I will say that it is absolutely imperative that General Petraeus come and testify. He was CIA director at the time of the attack. He visited Libya after the attack. He has a great deal of information that we need in order to understand what went wrong."

Petraeus was to testify Thursday on Benghazi in front of the Senate Intelligence Committee. Acting CIA Director Mike Morrell will now be testifying in his place, but that has not stopped the calls on the Hill for Petraeus himself to testify on Benghazi.

"I think we should go ahead with Mike Morell and the way it is now set up," Sen. Dianne Feinstein, chairwoman of the Senate Intelligence Committee, said on MSNBC Monday. "But I also think that the community should know that this is not sufficient. And I have no doubt now that we will need to talk with David Petraeus and we will likely do that in closed session but it will be done one way or the other."

Collins, ranking member of the Senate Committee on Homeland Security, said today she is "puzzled" by much of what has occurred in the FBI investigation into Petraeus' affair and specifically mentioned that it is concerning that his mistress, Paula Broadwell, may have had access to classified information.

When asked if the FBI informed the White House soon enough of the investigation Collins said there "does seem like there was an inordinate amount of time that passed," but added that without all the facts yet she doesn't want to reach any kind of conclusion.