(CNN) Sen. Susan Collins said Saturday that while she believes that Dr. Christine Blasey Ford was sexually assaulted, she does not believe that now-confirmed Supreme Court Justice Brett Kavanaugh did it.

"I do not believe that Brett Kavanaugh was her assailant," the Maine Republican told CNN's Dana Bash on "State of the Union" in an interview slated to air on Sunday. "I do believe that she was assaulted. I don't know by whom. I'm not certain when."

Ford accused Kavanaugh of sexually assaulting her while the two were in high school, prompting a week's delay in Kavanaugh's confirmation to allow the FBI to conduct an investigation into the alleged incident. Kavanaugh has denied all allegations.

Collins reviewed the results of the investigation, which included testimony from 10 different witnesses but not from Ford or Kavanaugh, on Friday. She then voted to advance Kavanaugh's nomination and has said that she will vote yes on Kavanaugh' during the full Senate's confirmation vote on Saturday.

Collins told Bash that while she found Ford's testimony "heart-wrenching," the fact that both Ford and Kavanaugh said they were "100 percent certain" of their statements meant that she had to look to the FBI for additional corroborating evidence.

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