The South Dakota attorney general’s office has declined to file charges against billionaire T. Denny Sanford following an investigation into possible possession of child pornography, saying it found no “prosecutable offenses” within the state’s jurisdiction, according to a court document filed Friday.

Sanford, a banker turned philanthropist, is the state’s richest man and has donated billions to hospitals, universities and charities. South Dakota investigators in 2019 began searching his email account, as well as his cellular and internet service providers, for possible possession of child pornography after his accounts were flagged by a technology firm.

The attorney general’s office said in Friday’s court filing that the “South Dakota Division of Criminal Investigation has completed its investigation ... and has determined that there are no prosecutable offenses within the jurisdiction of the State of South Dakota.”

The attorney general’s office had no comment beyond the court filing.

“Mr. Sanford appreciates the public acknowledgement by the SD Attorney General’s office that the DCI has concluded its investigation and they have found no prosecutable crime,” Marty Jackley, Sanford’s attorney, said via text.

South Dakota Attorney General Jason Ravnsborg had earlier requested the involvement of federal law enforcement. A state filing in January said both state and federal investigations were continuing at the time. The Department of Justice declined to comment Friday when asked if a federal investigation is ongoing.