The head of the Senate Judiciary Committee on Friday asked federal authorities to investigate a woman who made false sexual-assault claims against US Supreme Court Justice Brett Kavanaugh.

In a letter to the Justice Department and the FBI, Sen. Chuck Grassley (R-Iowa) said Judy Munro-Leighton accused Kavanaugh and a friend of raping her “several times each” in the backseat of a car — but investigators later found out she was a “left-wing activist” who is “decades older than Kavanaugh.”

The original accusation was made in a Sept. 19 letter to Sen. Kamala Harris (D-Calif.). A woman who identified herself as “Jane Doe” from Oceanside, Calif., detailed the episode in the car.

Harris forwarded the letter on Sept. 25 to the Senate Judiciary Committee investigators.

The allegation came amid a number of other stories from women, including Dr. Christine Blasey Ford who testified that Kavanaugh sexually assaulted her at a high school party.

Kavanaugh was asked about the letter in a September conference call under oath and denied the allegations.

On Oct. 3, three days before Kavanaugh was sworn in, Munro-Leighton sent the Senate Judiciary staff an e-mail that claimed she was the Jane Doe from the letter sent to Harris.

Committee investigators tracked her down and found she lives in Kentucky, not California.

When they finally spoke with her Thursday, she claimed she wasn’t Jane Doe — but had heard about the letter and claimed to be Jane Doe so it would get more attention. She said she’d never met Kavanaugh, but was against his nomination.

“I was angry and I sent it out,” she reportedly said.

It’s unclear who wrote the first Jane Doe letter.

Grassley said looking into Munro-Leighton’s claims diverted resources on a time-sensitive manner.

The letter from Grassley marks the fourth request for a federal investigation into people involved in the Kavanaugh proceedings — including Julie Swetnick, who accused Kavanaugh of attending parties where women were gang-raped, her lawyer, Michael Avenatti, and a man who hasn’t been publicly identified.