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Democratic Sen. Chris Coons said Tuesday that the FBI's investigation into sexual misconduct allegations during confirmation hearings for Supreme Court Justice Brett Kavanaugh was a "sham."

During an interview with CNN's Alisyn Camerota on "New Day," the Delaware senator also said he's interested in figuring out who handled the probe and that a new investigation should be opened into the allegations by two women who came forward last year.

"The question that we don't have answered, Alisyn, is given that that investigation is a sham, at whose direction did that happen? The FBI doesn't just make these things up. They were acting in response to a client, whether they considered that White House counsel or the Senate Judiciary Committee majority," Coons said.

Coons' comments come in the wake of new developments in the Kavanaugh saga, which began a year ago after allegations of sexual misconduct surfaced against the nominee during the confirmation process. Following an outcry from congressional Democrats, including Coons, who sits on the Senate Judiciary Committee, the FBI opened a supplemental background investigation into Kavanaugh, which ultimately found none of the allegations to be true. Kavanaugh has vehemently denied all of the allegations against him.

Sen. Chuck Grassley, who chaired the Judiciary Committee during Kavanaugh's confirmation, defended the committee's review of allegations against Kavanaugh, calling it "incredibly thorough" and saying "in the end there was no credible evidence to support any of the allegations."

CNN reported last year that the FBI's supplemental investigation was limited in scope from the beginning. Last year, Senate Republicans and the White House say they allowed the FBI to pursue leads within the parameters that Sen. Jeff Flake and other undecided Republican senators agreed to: credible, current allegations against Kavanaugh.

Asked by Camerota if he thinks Kavanaugh should be on the Supreme Court, Coons replied: "Look, I want this question answered: at whose direction was this narrowed? Why didn't a more fulsome investigation happened? I think that frankly Judge Kavanaugh and the American people and certainly Dr. (Christine Blasey) Ford and Ms. (Deborah) Ramirez deserved the sort of fuller investigation that was entirely possible within a week, and I'm hoping that's what will happen next."

A new book by two New York Times reporters which details the contentious confirmation fight including the sexual misconduct allegations against Kavanaugh which he has previously denied was released Tuesday. The book contains at least one new allegation from a former male classmate, Max Stier, who sources told the authors has come forward to the senators concerning an incident he witnessed involving Kavanaugh and another female student at Yale.

CNN reported on Monday that days before Kavanaugh's confirmation, Coons urged the FBI in a letter to reach out to a witness who had key information about alleged misconduct by the nominee while he was a student at Yale.

The book's authors said "Stier relayed his recollections to senators during the confirmation process and later made clear his willingness to share them with the FBI, but he refused to speak about them publicly." Stier declined to comment to CNN. The female victim declined to be interviewed by the book's authors, and her friends told the authors she does not recall the incident.

Additionally, the book reports that the FBI did not investigate this incident. The FBI declined to respond when asked about the allegation.

CNN is not reporting any details of the accusation and has not independently corroborated the account.

In a letter dated October 2, 2018, Coons sent a letter to the FBI requesting that the agency talk to individuals that had more information about Kavanaugh. Specifically, Coons suggested the FBI talk to Stier. It's unclear from the letter exactly what information Stier had, but Coons suggests the FBI talk to him. Stier's name in the letter is redacted in the version seen by CNN, but an aide for Coons told CNN that that the name was Stier's. Coons had copied Grassley, an Iowa Republican, and the judiciary committee's top Democrat, Sen. Dianne Feinstein of California.

An aide familiar with the letter told CNN that the FBI acknowledged receipt of Coons' letter at the time, but the senator never heard more beyond that.

CNN's Lauren Fox, Manu Raju and Ariane de Vogue contributed to this report.