Ina Thea Kenoyer, a 48-year-old woman in North Dakota, could spend the rest of her life in prison after pleading guilty to murdering her husband last year by poisoning him with antifreeze. The woman’s goal was to seize the man’s multimillion-dollar inheritance, which turned out not to exist.
On Wednesday, Kenoyer pleaded guilty to first-degree murder in the death of Steven Edward Riley Jr., 51, in 2023. Court records reviewed by Law&Crime confirm his guilty plea.
The investigation began on September 3, 2023, when Riley was transferred to Trinity Hospital in Minot, North Dakota, due to his serious health condition. He was subsequently flown to CHI Alexius Hospital in Bismarck, where he died on September 5.
An autopsy revealed that Riley died of poisoning from ethylene glycol, the main component of antifreeze, and authorities determined the manner of death was homicide.
Approximately two months later, on October 30, 2023, police arrested Kenoyer, citing “financial reasons” for the murder. Since her arrest, Kenoyer has been held on $1 million cash bail.
“This case was extremely complex,” Capt. Dale Plessas, commander of investigations, said in a statement. “Thank you to everyone who provided us with information that helped our investigators piece this together.”
According to a report from the Minot Daily News, friends and family of Riley informed investigators that Kenoyer had previously talked about poisoning her longtime boyfriend with antifreeze. They also noted that Kenoyer suddenly began claiming that Riley had been poisoned by someone while she was in the hospital.
Non-existent inheritance
The motive for the murder originated in a scam over an alleged $30 million inheritance that a distant relative had left to Riley. Both Kenoyer and Riley believed in the false inheritance, reported KXMB, a CBS affiliate in Bismarck.
After finding out about the inheritance, Riley began telling friends that she planned to leave Kenoyer and split the money between himself and her children. Kenoyer, when speaking with police, stated that he knew of the inheritance and believed he would be entitled to a share of it as Riley’s common-law partner.
However, detectives informed him that North Dakota does not recognize common-law marriages, causing Kenoyer to become visibly upset, according to the Minot Daily News.
During the execution of a search warrant at the couple’s home, police found a glass beer mug and a plastic beer mug in the garage, both with traces of antifreeze. Kenoyer eventually admitted to putting antifreeze in a cup of Riley’s sweet tea with the intention of killing him.
Kenoyer will appear before Judge Richard L. Hagar of the North Central Judicial District Court on August 13 for his sentencing hearing. She faces the possibility of life in prison without the possibility of parole, which could mean she spends the rest of her life in a state correctional facility.
With information from Law&Crime.
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