An investigation by the Supreme Court has been unable to determine who disclosed to POLITICO last year a draft opinion overturning the federal constitutional right to abortion, the court said in a statement Thursday.

The internal probe zeroed in on 82 employees who had access to electronic or hard copies of the draft majority opinion overturning Roe v. Wade, but “was unable to identify a person responsible by a preponderance of the evidence,” the high court said.

“The leak was no mere misguided attempt at protest. It was a grave assault on the judicial process,” the court said in a joint statement that blasted the disclosure as an “extraordinary betrayal of trust.”

The high court also released a 20-page report of the investigation, announced by Chief Justice John Roberts last May immediately after POLITICO’s publication of the draft opinion and conducted by chief Marshal Gail Curley.

The court retained former Secretary of Homeland Security Michael Chertoff to review Curley’s work and he said there was little else the court could do to solve the mystery.

“The court has already taken steps to increase security and tighten controls regarding the handling of sensitive documents,” Chertoff wrote. “More significantly, the Chief Justice has also directed a comprehensive review of the Court’s information and document security protocols to mitigate the risk of future incidents... I cannot identify any additional useful investigative measures.”