A well-known South Dakota medicine man who had been charged with abusing and raping at least six girls on the Pine Ridge Indian Reservation died in prison Tuesday night, according to law enforcement officials.

Charles Chipps Sr., 67, was being held in a federal prison in Springfield, Mo., awaiting trial, when he became ill and died, according to U.S. Attorney Brendan V. Johnson, who was prosecuting the case against Chipps.

Johnson, who did not know Chipps’s cause of death, said he will have to drop the charges.

“This is not at all an indication of how we view the case,” Johnson said. “But we obviously cannot proceed without a defendant.” He added: “We are continuing to provide support to the victims in this case as they deal with a myriad of emotions.”

Chipps’s attorney, Terry L. Pechota, said Chipps had suffered from kidney failure, but he also did not know the cause of death. Chipps had recently been in a hospital for several days but was returned to the prison, where he died, Pechota said.

Medicine man Charles Chipps, who was awaiting trial on rape charges, died in prison Tuesday, Jan. 20, 2015. (Obtained by The Washington Post)

In an interview last month, Pechota told The Washington Post that Chipps was suffering from diabetes, high blood pressure and congestive heart failure and was not mentally competent to stand trial.

“Charles Chipps has not been convicted of anything,” Pechota said Wednesday. “He left a legacy of helping people. He was a true medicine man. He had a vast network of supporters across the United States. There’s certainly nothing proven that would tarnish that legacy he will leave.”

In a case highlighted by The Post, Chipps was arrested in Wanblee in 2009 by tribal police on tribal child sex abuse charges and was detained in a Pine Ridge jail.

Although the nation’s 566 Indian tribes have their own governments and court systems, the prosecution of felony crimes such as sexual assault and rape generally falls to the U.S. Justice Department. In the case of Chipps, the U.S. Attorney’s Office for the District of South Dakota opened an investigation but did not have enough evidence to bring federal charges at that time. After a year, Chipps was released.

Three years later, a federal grand jury indicted Chipps on 15 counts of rape, sexual abuse and intimidation of six minor victims.

Along with the children in the indictment, older victims from South Dakota and other states came forward with allegations that Chipps had sexually abused them when they were younger, according to a filing by the U.S. attorney’s office. Chipps pleaded not guilty.

Pechota said he is trying to make arrangements for Chipps’s body to be returned to South Dakota for burial in the community of Wanblee on Pine Ridge, where Chipps had lived with his family.