Leland Keyser stood to be the perfect witness for Christine Blasey Ford by confirming critical events that would bolster her charges against Supreme Court nominee Brett Kavanaugh.

But she wasn’t.

She has ended up helping the nominee on two crucial questions as the confirmation process shifts from emotion-filled hearings on Thursday to a one-week FBI investigation.

Ms. Keyser was among Ms. Ford’s best friends at Holton-Arms, the all-girl private school in Bethesda not far from Mr. Kavanaugh’s boy-only Georgetown Preparatory.

As best friends to this day, it was expected that Ms. Keyser would confirm Ms. Ford assertions: Ms. Keyser was with her on the night sometime in 1982 that Mr. Kavanaugh sexually assaulted her in an upstairs bedroom in a home in Chevy Chase or Bethesda during a lightly attended party. She also said Ms. Keyser socialized with the other attendees, meaning Mr. Kavanaugh.

Before this week’s Ford-Kavanaugh hearing, Ms. Keyser sent an email to the Senate Judiciary Committee, via her attorney Howard J. Walsh III, denying this. She has no recollection of such a party, she said.

“Simply put, Ms. Keyser does not know Mr. Kavanaugh and she has no recollection of ever being at a party or gathering where he was present, with, or without, Dr. Ford,” Mr. Walsh said.

On Saturday morning, after President Trump authorized a one-week FBI probe into Ms. Ford’s charges, Mr. Walsh again repeated her denial in a new statement to committee staff.

“Ms. Keyser asked that I communicate to the Committee her willingness to cooperate fully with the FBI’s supplemental investigation of Dr. Christine Ford’s allegations against Judge Brett Kavanaugh,” Mr. Walsh said. “However, as my client has already made clear, she does not know Judge Kavanaugh and has no recollection of ever being at a party or gathering where he was present, with, or without, Dr. Ford.”

The fact Ms. Keyser says she didn’t know Mr. Kavanaugh in those days is another set back for Ms. Ford.

Ms. Ford, a psychologist, says she herself met Mr. Kavanaugh as the two traveled in similar social circles.

Mr. Kavanaugh told committee staff they moved in different circles and he never met her, though he had heard the name.

If Ms. Ford did attend the same gatherings as teenage Kavanaugh, a question would be why didn’t her best friend know him?

In her testimony on Thursday, Ms. Ford brushed aside Ms. Keyser’s lack of corroboration.

“Do you have any particular motives to ascribe to Leland?,” asked Rachel Mitchell, a career sexual crime prosecutor hired by committee Republicans.

Ms. Ford: “Leland has significant health challenges, and I’m happy that she’s focusing on herself and getting the health treatment that she needs, and she let me know that she needed her lawyer to take care of this for her, and she texted me right afterward with an apology and good wishes, and et cetera, So I’m glad that she’s taking care of herself. I don’t expect that P.J. and Leland would remember this evening. It was a very unremarkable party. It was not one of their more notorious parties, because nothing remarkable happened to them that evening. They were downstairs.”

“P.J.” is Patrick J. Smyth, a friend of Mr. Kavanaugh’s. He has told the committee he was not at the supposed party.

Mark Judge, who Ms. Ford said took part in the assault, has told the committee he has no memory of the party. He is an admitted alcoholic.

Ms. Ford, then 15, said she escaped the two, went down the stairs and out of the house. She said she doesn’t know how she made it home, but was not driven. She doesn’t know the house’s location or the week or month it happened.

Ms. Mitchell asked what she told Ms. Keyser the next day.

“Oh no, she didn’t know about the event. She was downstairs during the event and I did not share it with her,” she answered.

Ms. Mitchell asked if any one has come forward to say “Hey, I was at that party too.”?

“No, I haven’t talked with anyone from that party,” she said.

In attorney Walsh’s Saturday email to the committee, he said Ms. Keyser believes Ms. Ford’s a account.

“However, the simple and unchangeable truth is that she is unable to corroborate it because she has no recollection of the incident in question,” Mr. Walsh said.