South Dakota Supreme Court Orders New Trial for Man Convicted in Girlfriend’s 2020 Death

RAPID CITY, SOUTH DAKOTA — The South Dakota Supreme Court has ordered a new trial for a Rapid City man convicted of first-degree murder in the 2020 shooting death of his girlfriend, ruling that the trial court made significant errors in admitting prior acts as evidence.

Conviction Overturned After Evidence Dispute

Dion Bordeaux, of Rapid City, was sentenced to life in prison without parole in 2023 after a Pennington County jury found him guilty of killing Jeanette Jumping Eagle during a domestic dispute. Prosecutors argued Bordeaux shot Jumping Eagle after an argument, while the defense maintained that she had taken her own life after Bordeaux ended their relationship.

During his appeal, Bordeaux’s attorneys contended that the lower court abused its discretion by allowing jurors to hear about unrelated prior incidents, including a drug conviction and an alleged attempted murder. They argued that such evidence unfairly influenced the jury’s perception of Bordeaux’s character rather than focusing solely on the events surrounding Jumping Eagle’s death.

Supreme Court Split but Rules in Bordeaux’s Favor

In its October 16 ruling, all five justices agreed that the trial judge erred by allowing inadmissible prior acts to be presented during the proceedings. However, the court was divided 3–2 on whether that error warranted a full retrial.

The majority opinion concluded that the admission of the past incidents likely impacted the jury’s decision-making, undermining the fairness of the trial. As a result, Bordeaux’s conviction was vacated, and a new trial was ordered in Pennington County Circuit Court.

The minority opinion, written by two dissenting justices, expressed that while the trial court’s decision was questionable, it did not materially alter the case’s outcome given the weight of the evidence against Bordeaux.

Case Returns to Lower Court for Rehearing

The ruling means Bordeaux will once again face prosecution for the 2020 killing, nearly five years after the death of Jumping Eagle, which shocked the Rapid City community. No timeline has been announced for when the retrial will begin.

Legal analysts note that the Supreme Court’s decision underscores a key principle in criminal law — that defendants must be judged solely on the evidence tied to the crime, not on prior conduct or unrelated history.

The South Dakota Attorney General’s Office and Pennington County State’s Attorney’s Office have not yet commented on whether they plan to appeal or modify their strategy ahead of the new proceedings.

The 2020 case remains one of Rapid City’s most closely followed homicide trials, highlighting the complex intersection of domestic violence, mental health, and criminal procedure in the state’s legal system.

As the case heads back to court, both legal teams are expected to revisit witness testimony, forensic reports, and the timeline surrounding Jumping Eagle’s death. The outcome of the retrial could reshape the conversation around how prior acts are used in South Dakota criminal cases.

For updates on this developing case and other South Dakota legal news, readers can follow continuing coverage at NapervilleLocal.com, where community, law, and justice intersect across the Midwest.