On March 8, 1992, Rhines used a copy of the back door key to enter Dig 'Em Donuts. It was a Sunday and the donut shop was closed, so nobody was inside. Rhines began absconding with money from the cash register when he was interrupted by Donnivan Schaeffer, a 22 year old employee who worked as a courier and came there to pick up supplies. Rhines ran at Schaeffer with a knife and stabbed him in the chest. Schaeffer begged to be taken to the hospital and swore he wouldn't tell anyone, but Rhines pushed him into a storage locker, tied him, and stabbed him to death. He stole $3,000 in cash and fled. Schaeffer's body was found the next day and Rhines attended the funeral with his roommate. Shortly afterwards he skipped down and made his way to Washington.

Immediately suspected in the robbery/murder, Rhines was apprehended in Seattle on June 19 but it was more than two months before he was finally extradicted to South Dakota. He readily confessed to everything, but prosecutors would not accept a plea bargain and sought the death penalty which in South Dakota requires a unanimous jury verdict. The jury found him guilty on January 26, 1993 on the grounds that the murder was committed in the commission of another crime, that it was premeditated, and that it was exceptionally heinous or cruel to the victim.

Schaeffer was initially stabbed in both lungs which would cause painful, labored breathing but not be immediately fatal. The fatal wound was a knife thrust to the back of the skull, puncturing the brain stem and essentially like being decapitated. According to Rhines's confession, Schaeffer continued to breathe and move around his arms after this injury, so he tied them behind his back. He reckoned that Schaeffer breathed for about two minutes afterward. The forensic pathologist who examined the body acknowledged that it was possible that his limbs made some involuntary death spasms.