WASHINGTON — The Supreme Court on Thursday announced that it has not been able to identify the person who leaked an unpublished draft of an opinion indicating that the court was about to roll back the right to abortion.

In an unsigned statement, the court said all leads had been followed up and forensic analysis had been carried out, but «to date, the team has been unable to identify a person responsible due to a preponderance of the evidence.»

In an accompanying report, Chief Justice Gail Curley, who is leading the investigation, said 97 court employees were interviewed and all denied being the informants. She said it was unlikely that the court’s information technology systems were compromised.

“Investigators continue to review and process some electronic data that has been collected and some other inquiries are still pending. To the extent that additional research yields new evidence or leads, investigators will pursue them,» Curley wrote.

“If a court employee released the draft opinion, that person was in flagrant breach of a system that was fundamentally built on trust with limited safeguards to regulate and restrict access to highly sensitive information,” it added.

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

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

«At this time, I am unable to identify any additional useful investigative measures,» he added.

Washington was rocked in May of last year when Politico released a draft opinion written by Justice Samuel Alito indicating that the court, which has a 6-3 conservative majority, was on the verge of overturning Roe v. Wade, the historic ruling on the right to abortion.

Traditionally, the internal operations of the court are shrouded in secrecy, and it is highly unusual for signs of internal deliberations to leak out before a ruling is issued. A day later, Chief Justice John Roberts confirmed the draft was genuine, saying it heralded an investigation into the leak.

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

The Politico report sparked abortion rights protests, prompting the court to erect a security fence around the building. In the months that followed, there were protests at the homes of some judges, and a man was charged with attempted murder after he was arrested near the home of conservative judge Brett Kavanaugh while he was in possession of a gun.

The following month, the court struck out Roe in a 5-4 vote, but in the months since 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 over the inner workings of the court. Liberal justices have suggested that the court risks undermining its legitimacy by abruptly unraveling decades of precedent.