RAPID CITY, S.D. – A 30-year-old man has been sentenced to 45 years in prison for the brutal stabbing death of 21-year-old William “Willis” Medicine Eagle, a young man whose family described him as a protector of others and a light in the lives of those who knew him.

Joseph Poor Thunder, a previously convicted felon, pleaded guilty to first-degree manslaughter in July 2026. As part of a plea agreement, Poor Thunder agreed to participate in a restorative justice process with the victim’s family. The State agreed to recommend no more than 45 years in prison.

During sentencing, Chief Deputy State’s Attorney Adam Shiffermiller told the court that one of the most troubling aspects of the case is a question that may never be answered: Why?

Poor Thunder stabbed Medicine Eagle five times and left him to die. He was intoxicated at the time of the killing and claims he has no memory of the attack or what motivated it.

Numerous family members and friends addressed the court, describing a young man whose life was filled with promise and whose loss has left an immeasurable void. One after another, they urged the judge to impose a life sentence.

Rebecca Kidder, Medicine Eagle’s adoptive mother, or Ina in Lakota, described her son as “pure light and medicine.” His biological mother, Heather Wright Robinson, remembered him as someone who stood up for others and whose presence could light up a room.

“It took a lot of hate to extinguish our son’s life,” Kidder told the court as she pleaded for the maximum sentence.

Before imposing the sentence, Seventh Circuit Judge Matthew Brown condemned Poor Thunder’s actions, calling the violence “barbaric” and “unnecessary.” Judge Brown said he believed the killing was committed consciously and with a dark heart.

Despite a request from Poor Thunder’s defense attorney to suspend a portion of the prison term, Judge Brown imposed the full 45-year sentence contemplated by the plea agreement.

First-degree manslaughter is a Class C felony in South Dakota, punishable by up to life in prison and a fine of up to $50,000.

“Willis Medicine Eagle had a family who loved him, people who looked up to him and an entire life that should have been ahead of him,” said Chief Deputy State’s Attorney Adam Shiffermiller. “No prison sentence can undo that loss or give this family back what was stolen from them. But today, we are grateful that Joseph Poor Thunder has been held accountable for taking Willis’ life.”

The case was prosecuted on behalf of the State by Chief Deputy State’s Attorney Adam Shiffermiller.