SIOUX FALLS, S.D. (AP) — 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.

Ravnsborg is on leave pending his trial in June on impeachment charges for his conduct after he struck and killed a pedestrian with his car in 2020.

A person briefed on the matter by law enforcement told The Associated Press last year that Sanford’s electronic devices came to the attention of state investigators after a technology firm reported that child pornography had either been sent, received or downloaded on his device. The person was not allowed to discuss the case at the time and spoke on condition of anonymity.

The investigation was first reported in 2020 by ProPublica and the Sioux Falls Argus Leader. Both news outlets went to court for access to affidavits for search warrants. As part of arguments in state court over the release of the documents, Jackley said the investigation revealed that his client’s email accounts were hacked.

The search warrant affidavits were still not publicly available as of Friday evening. Judge James Power told the Argus Leader he expected to release them on Tuesday, but the newspaper also reported that Sanford attorney Stacy Hegge had moved to delay the unsealing.

The 86-year-old Sanford is worth an estimated $3.4 billion. He made a fortune as the founder of First Premier Bank in South Dakota, which is known for issuing high-interest credit cards to those with poor credit.

Sanford told the The Associated Press in 2016 that he wanted his fortune to have a positive impact on children after his hardscrabble childhood in St. Paul, Minnesota. His mother died of breast cancer when he was 4, and by the time he was 8, Sanford was working in his father’s clothing distribution company. He, along with two siblings, lived in a small apartment.

“You can only have so many cars and all of that kind of stuff so put it into something in which you can change people’s lives,” Sanford said in 2016.

After the investigation into Sanford became public, his financial largesse hardly slowed. In January, he donated $50 million to a Dakota State University cybersecurity lab while the hospital system that bears his name, Sanford Health, received over $650 million in donations from him last year.