Officials said that in a typical supplemental background check inquiry, agents would be required to ask the White House for permission to expand beyond the initial list of interview subjects.
But they insisted that the F.B.I. was not required to do that in the case of the allegations against Judge Kavanaugh. Over the course of the week, they said, agents decided to add a handful of other interviews to the inquiry.
According to a list distributed by the Senate Judiciary Committee, F.B.I. agents also interviewed Timothy Gaudette and Christopher Garrett, two high school friends of Judge Kavanaugh who were listed in the judge’s 1982 calendar as having attended a high school party. In addition, agents interviewed a lawyer of one of the friends.
Agents also interviewed two potential eyewitnesses to the episode alleged by Ms. Ramirez, as well as one of her close friends. The F.B.I. did not identify the three, but two of them were Kevin Genda and Karen Yarasavage, who are now married and knew Ms. Ramirez and Mr. Kavanaugh in college
.. Mr. Genda and Ms. Yarasavage were each interviewed for more than two hours, according to the lawyer.
In addition, the F.B.I. agents collected written statements that had been submitted to them from other people, officials said. Those statements were also sent to the White House and forwarded to the Senate Judiciary Committee, officials said.
White House officials insisted that neither Mr. McGahn nor any other West Wing lawyer prohibited the F.B.I. from interviewing them. But some former law enforcement experts said it was an odd decision not to include the two people at the center of the controversy .
Robert Cromwell, a former F.B.I. agent who oversaw sensitive background investigations of political appointees, doubted that agents decided not to interview Dr. Blasey and Mr. Kavanaugh on their own.
“I don’t think that it was in the parameters of the request ,” he said. “That’s what I would assume. It would be frustrating as an investigator. The nature of investigators is to get to the bottom line. You’d want to talk to both of them.”