A federal jury in Rapid City, South Dakota, has found Reno Rondeau, 52, of Manderson, guilty of first degree felony murder, assault with intent to commit arson, assault resulting in serious bodily injury, and arson. The verdict was delivered on February 5, 2026, after a three-day trial.
Rondeau faces a mandatory life sentence in prison and could be fined up to $250,000. He is also subject to a $400 special assessment payable to the Federal Crime Victims Fund.
The charges stem from an incident in October 2024 when Rondeau set fire to his brother’s home near Manderson. At the time of the fire, both his brother and Tanya White Butterfly were inside the residence. White Butterfly, who had previously worked as a correctional officer for the Oglala Sioux Tribe, died in the fire. John Rondeau Sr., Reno’s brother, managed to escape but suffered burn injuries while attempting to rescue White Butterfly. The house was destroyed.
The case was prosecuted federally under the Major Crimes Act because it involved violent crimes that occurred in Indian country.
The investigation involved multiple agencies: the Oglala Sioux Tribe Department of Public Safety, the Federal Bureau of Investigation (FBI), and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). Assistant U.S. Attorneys Heather Knox and Paige Petersen led the prosecution.
A presentence investigation has been ordered. Sentencing is scheduled for May 18, 2026. Rondeau remains in custody with the U.S. Marshals Service pending sentencing.
