MOUNT PLEASANT, Iowa — It took a jury less than an hour Tuesday to return with a guilty verdict for an Iowa man charged with murder in the death of his infant son, who prosecutors said was left in a baby swing -- without formula or clean diapers -- for more than a week.
Zachary Paul Koehn showed little emotion as he was convicted of first-degree murder and child endangerment causing death, The Waterloo-Cedar Falls Courier reported. Koehn, 29, faces a mandatory life sentence on the murder charge. His sentencing will be held at a later date.
Koehn’s former girlfriend, 21-year-old Cheyanne Renae Harris, has also been charged with murder and child endangerment in their son’s death and is awaiting trial, the newspaper reported. Like Koehn, she was granted a change of venue due to pretrial publicity.
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Warning: This story contains extremely graphic details of a child’s death.
Sterling Daniel Koehn, 4 months old, was found dead on Aug. 30, 2017, at his parents' Alta Vista apartment. According to the medical examiner, evidence showed that neither Zachary Koehn nor Harris had removed the baby from the swing, bathed him or changed his diaper in up to 14 days.
The baby only weighed a few ounces more than his birth weight when he died, pathologist Dr. Dennis Klein testified. He weighed less than 7 pounds when Klein weighed him during his autopsy.
A social worker with the Iowa Department of Human Services testified that Sterling, who was born in a bathtub at the home of a family friend, had signs of neglect from the time he was born, the Courier reported. Sheila Schroeder told jurors that the newborn's umbilical cord tested positive for methamphetamine at the hospital.
The hospital never informed DHS social workers of the positive test, Schroeder testified. State social workers did not learn about the finding until after Sterling died, at which time his then-2-year-old sister was removed from Koehn and Harris’ care.
Schroeder told the court that Koehn, who laughed throughout his meeting with her two days after his son died, told her he thought the boy died of Sudden Infant Death Syndrome, or SIDS. He admitted during that meeting that both he and Harris used meth.
Klein testified that Sterling died of a combination of infection, malnutrition and dehydration, each of which were serious enough on their own to have caused his death, the Courier reported.
"Nothing natural would have caused this," Klein said, according to the newspaper.
The infection was caused when Sterling developed diaper rash from his dirty diaper, the feces left against his skin eventually breaking it down. The rash, which became infected with e. Coli bacteria, attracted bugs that laid eggs in his diaper.
Maggots and their larvae were found in the boy’s diaper and clothes at his autopsy.
Klein said the maggots were likely beginning to hatch while the baby was still alive, the newspaper reported. That viewpoint was echoed by forensic entomologist Timothy Huntington, who testified that the bugs on Sterling's body indicated his diaper had not been changed in at least nine days.
Medics and sheriff's deputies testified during the trial about finding Sterling cold and stiff when they were called to the family's apartment. The baby was found in his swing in a hot bedroom, his clothes crusted over and blankets reeking of urine. Gnats flew around the baby's body when the blankets were moved, one Chickasaw County medic said.
“His eyes were open, and it was a blank stare,” the medic testified.
Koehn's attorney argued that his client, who worked nights as a truck driver, was away from home and providing for his family as his son was fatally neglected by Harris, who did not work outside the home. According to the Courier, defense lawyer Steven Drahozal said Koehn never noticed any signs that Harris, who was Sterling's primary caretaker, may have been depressed enough to keep her from caring for their son.
Denise Timmons, one of the assistant attorneys general prosecuting Koehn, said that each time Koehn came home from work and did nothing to help his son, he engaged in a separate act of neglect, the Courier reported.
"He let Sterling rot in that room," Timmons said, according to the newspaper. "He left him there to die."
Timmons’ co-counsel hammered at Koehn when he took the stand in his own defense Friday. Koehn told jurors multiple times that he “put his trust in the wrong person” when he left Harris to care for their son while he was away.
Assistant Attorney General Coleman McAllister questioned why Koehn, Harris and their 2-year-old daughter were all healthy and well-fed even as Sterling was dying in a back bedroom.
"Would you agree you took better care of Leo (the family dog) than you did your own son?" McAllister asked him, according to the Courier.
“Um, the way it looks, yes,” Koehn responded.
Koehn also testified about growing up in the Mennonite faith, which defense witnesses testified teaches that a father is supposed to earn a living and a mother is responsible for child care. He told the court he typically worked 70 to 80 hours per week hauling live chickens, the Courier said.
Expelled from the Mennonite faith at 16 for drinking and smoking, Koehn admitted that he started using meth a year later to stay awake while on the road. Harris also used meth, Koehn testified.
A friend of the couple testified earlier in the trial that he sold meth to Koehn and occasionally visited him and Harris at their apartment. Jordan Clark told the court that though he knew about the couple's 2-year-old daughter, he had no idea they had an infant son, despite those visits.
Koehn said he quit using meth about two weeks before his son died and testified he went to Twin Falls, Minnesota, the weekend before Sterling's death to trade leftover meth for baby supplies, the Courier reported. He also testified that despite noticing a foul smell in the bedroom where Sterling was two days before he died, he had no idea the stench was coming from his son.
Koehn said he removed a trash bag full of dirty diapers at that time and thought the remaining smell was a lingering odor from the bag. He said a “weak stomach” kept him from changing his children’s diapers, though he occasionally fed Sterling a bottle.
A deputy previously testified that he found a bottle near the baby's swing that contained formula that had begun to separate. Cans of fresh formula were found in the kitchen of the home.
Koehn said his son was typically asleep when he was home from work and he would not wake him because the infant had colic.
"I was not to disturb him when he was sleeping," Koehn testified, according to the Courier.
The defendant's testimony, during which he said he played with his son two days before the boy died, was at odds with that of Klein, who said that in Sterling's final days, he would have been weak and lethargic and unable to interact with those around him. He also wound have been unable to cry, the medical examiner said.