Jury selection began Tuesday in Lee County for the murder trial of an inmate accused of killing another prisoner at the Iowa State Penitentiary in December 2024.
Anthony Michael Koehlhoeffer, 35, is charged with second degree murder, a Class B felony, in connection with the death of 64-year-old inmate Gary Showalter Sr.
According to a criminal complaint, the assault happened around 4 p.m. on December 19, 2024, inside the prison kitchen where both men were assigned to cleaning duties. Investigators say the two inmates became involved in a verbal altercation before Koehlhoeffer initially began walking away.
Authorities say Showalter continued speaking to him, prompting Koehlhoeffer to turn around, walk back, and shove Showalter to the floor. Surveillance video reportedly shows Koehlhoeffer standing over Showalter and repeatedly punching, kicking, and stomping his head and face for approximately 25 seconds. Court documents state Koehlhoeffer punched Showalter in the head 21 times and kicked or stomped him seven times. Investigators say several of those blows occurred after Showalter appeared to lose consciousness.
Body camera footage from correctional officers following the incident allegedly captured Koehlhoeffer telling an officer that Showalter “brought it upon himself.” Authorities also say recorded prison phone calls include statements from Koehlhoeffer discussing the assault.
Showalter was transported to the University of Iowa Health Care Medical Center following the incident and later died on December 28, 2024. An autopsy determined the cause of death was blunt force injuries to the head, and the manner of death was ruled a homicide.
The Iowa Division of Criminal Investigation was called to investigate the case. Koehlhoeffer was formally charged on March 26, 2025, and entered a not guilty plea on May 16.
Showalter had been serving a life sentence without the possibility of parole after being convicted in 2023 of first degree murder in the death of his wife, Helen Showalter of Ottumwa.
Koehlhoeffer is currently incarcerated for a 2010 second degree robbery conviction in Jefferson County related to the robbery of the Pilot Grove Savings Bank in Fairfield.
The jury trial is being held at the North Lee County Courthouse in Fort Madison.