A federal judge on Friday ended his investigation into information leaked to newspapers about secret grand jury proceedings against officers involved in George Floyd's murder.

Chief U.S. District Judge Patrick Schiltz stopped the probe, which began in May 2021, after an extensive review by state and federal law enforcement failed to uncover the source of the leaks that led to stories published by the Star Tribune and the New York Times. The leaked information detailed the possibility of federal charges against the officers.

"The Court is disappointed that the sources of the grand jury information were not identified, particularly because one or more of those sources may have committed a crime and may have been a prosecutor or law enforcement officer who had sworn to uphold the law," wrote Schiltz, who became the District of Minnesota's chief judge earlier this month. "At this point, however, the Court reluctantly acknowledges that there is nothing more that can be done to identify the sources of the grand jury material. The Court orders that this matter be closed."

Schiltz had ordered the U.S. Attorney's Office and Minnesota Attorney General's Office to list every person to whom they disclosed grand jury activity. Schiltz also ordered the U.S. Attorney's Office to explain why he should not appoint an independent prosecutor to investigate for potential criminal contempt-of-court charges.

Schiltz's order dismissing the case on Friday disclosed that the parties collectively identified "well over 100 people who had access to grand jury matters." The U.S. Justice Department, FBI, U.S. Marshals Service and the Minnesota Attorney General Office each initiated internal inquiries, while the FBI opened a separate, external investigation.

"Based on the initiation of these investigations, the Court determined that it was not necessary to appoint a special prosecutor," Schiltz wrote.

Schiltz described the investigations as thorough: The U.S. Attorney's Office and Justice Department submitted more than 60 declarations from attorneys and staff members, "each attesting under penalty of perjury that the declarant did not disclose to the media the grand jury information that appeared in the newspaper articles."

During internal investigations, the federal entities gathered more than 100 similar sworn declarations and the state collected more than 50, "each attesting either that the declarant had no actual knowledge of any confidential grand jury information or that the declarant had such knowledge but did not make any unauthorized disclosures."

State investigators interviewed additional people with knowledge of grand jury matters, and the FBI interviewed dozens of people. Investigators combed through electronic devices and reviewed hundreds of documents, including e-mails, Schiltz wrote.

"After two exhaustive investigations, the court's order reflects what was obvious to me from the start that the Chauvin prosecution team was never the source of any alleged leak," Minnesota Attorney General Keith Ellison said in a statement on Friday. "We voluntarily conducted our own thorough internal investigation and complied fully and willingly with the thorough FBI investigation."

Schiltz assessed that investigators failed to identify the sources of the leak based, at least partly, on two factors: an extraordinarily large number of people who had access to grand jury material supplied by federal and state law enforcement sources and a Justice Department policy that restricts the use of "compulsory legal process" to gather information or records from reporters.

"Thus, the FBI was blocked from obtaining evidence from the reporters, who, of course, almost certainly knew who had provided grand jury information to them," Schiltz wrote.

Randy Lebedoff, senior vice president and general counsel for the Star Tribune, said in a statement Friday, "I am glad the court has ended this costly and intimidating hunt for information which was always protected under the First Amendment."

Former Minneapolis officer Derek Chauvin was sentenced to more than 20 years in prison earlier this month for violating Floyd's civil rights and those of a Black Minneapolis teenager three years before Floyd's death. Chauvin's sentence will be served concurrently with the 22½ year term he already is serving for his state murder conviction. Three other former officers are awaiting federal sentencing after being convicted earlier this year on similar charges.