Former O’Reilly manager who choked man to death in KCK appeals 5-year sentence
A former O’Reilly Auto Parts store worker was sentenced to nearly five years in prison for choking a man to death whom he suspected of stealing at a Kansas City, Kansas, store, online court records show.
A Wyandotte County judge sentenced Carl R. Kemppainen to 57 months in prison with 24-month post-release monitoring conditions. He was also required to register as a violent offender for 15 years, according to court records.
In May, a jury convicted Kemppainen of involuntary manslaughter in the 2023 killing of 23-year-old Diamond Steen.
The killing happened at a KCK auto parts store. Steen, of Kansas City, was one of two men who police said were involved in a physical altercation with store employees after being suspected of stealing.
Man killed at auto parts store
On Sept. 19, 2023, Steen and another man police identified as Keysean Perkins had allegedly stolen two cans of car paint and sandpaper from the O’Reilly at 4700 Parallel Parkway, where Kemppainen was the store manager at the time.
According to court documents, video surveillance footage at O’Reilly showed Kemppainen run in front of Steen and Perkins as they tried to exit the store. He then followed them into the parking lot and tried to prevent them from leaving.
Kemppainen allegedly said in an interview with police officers that he had heard about two men stealing from another O’Reilly’s location a few days prior. He thought Steen and Perkins were the two suspected shoplifters, according to court documents.
After not allowing Steen and Perkins to get in their car, Kemppainen then allegedly placed Steen in a chokehold, according to court documents. Around that time, surveillance video showed another O’Reilly employee, Royal J. Ford, exiting the business and confronting Perkins on the passenger side of the car.
During the confrontation, Ford allegedly pulled Perkins away from the car and began to wrestle with him in an attempt to detain him, according to court documents.
Surveillance video allegedly showed Perkins lying face down on the ground as a third employee wrapped tape around his wrists, according to court documents. When Perkins tried to raise his head, Ford allegedly stomped down on Perkin’s neck and upper back, causing his face and chin to hit the ground, according to court documents.
Perkins got a small cut on his chin that required stitches at a hospital.
When officers responded to the store, they found Steen and Perkins bound in tape, bungie cords and zip ties by the front door, according to court documents. Steen was not responsive.
Officers had an O’Reilly employee cut the bindings, and police began CPR. Paramedics responded and pronounced Steen dead at the scene.
At a 2023 press conference, Wyandotte County District Attorney Mark Dupree said an autopsy confirmed Steen died of strangulation.
Ford was charged with misdemeanor battery for his involvement in the altercation with Perkins. He was sentenced in March 2024 to six months probation, which ended Sept. 1, 2024.
Ford and Kemppainen were named as defendants along with O’Reilly Automotive Stores in a civil suit filed by Perkins in September 2024. A confidential settlement agreement was reached in April 2025, according to court records.
Kemppainen is appealing his guilty verdict and sentencing for involuntary manslaughter, according to a notice of appeal filed by his attorneys Thursday.
Previous reporting by The Star’s Robert A. Cronkleton contributed to this story.
This story was originally published August 2, 2025 at 1:25 PM.
