WASHINGTON — The Supreme Court on Thursday announced that it has been unable to identify the person who leaked an unpublished draft of an opinion indicating the court was poised to roll back abortion rights.

In an unsigned statement, the court said that all leads had been followed up and forensic analysis performed, but “the team has to date been unable to identify a person responsible by a preponderance of the evidence.”

In an attached report, Supreme Court Marshal Gail Curley, who is in charge of the investigation, said that 97 court employees were interviewed and all denied being the leaker. She said it was unlikely the court’s information technology systems were compromised.

“Investigators continue to review and process some electronic data that has been collected and a few other inquiries remain pending. To the extent that additional investigation yields new evidence or leads, the investigators will pursue them,” Curley wrote.

“If a court employee disclosed the draft opinion, that person brazenly violated a system that was built fundamentally on trust with limited safeguards to regulate and constrain access to very sensitive information,” she added.

The court also consulted Michael Chertoff, who served as Homeland Security secretary during the administration of President George W. Bush. Chertoff wrote in a separate statement that he had recommended several measures the court could take to improve security.

Chertoff said he had reviewed the investigation and concluded that it was conducted thoroughly.

“At this time, I cannot identify any additional useful investigative measures,” he added.

Washington was rocked in May of last year when Politico published a draft opinion authored by Justice Samuel Alito that indicated the court, which has a 6-3 conservative majority, was about to overturn Roe v. Wade, the landmark abortion rights ruling.

Traditionally, the court’s internal operations are shrouded in secrecy, and it is highly unusual for any signs of internal deliberations to be leaked before a ruling is issued. A day later, Chief Justice John Roberts confirmed that the draft was genuine and said he was announcing an investigation into the leak.

“To the extent this betrayal of the confidences of the court was intended to undermine the integrity of our operations, it will not succeed,” Roberts said. He called the leak “a singular and egregious breach” that was “an affront to the court.”

Politico’s report led to abortion rights protests, prompting the court to erect a security fence around the building. In the months following there were protests at the homes of some justices and one man was charged with attempted murder after being arrested near the home of conservative Justice Brett Kavanaugh while in possession of a handgun.

The following month, the court did indeed overturn Roe on a 5-4 vote, but in the months following there has been no official update on the status of the investigation.

The leak, in addition to the backlash to the abortion ruling, has led to increased scrutiny on the inner workings of the court. Liberal justices have suggested that the court risks undermining its legitimacy by abruptly unraveling decades of precedent.