North Dakota woman to serve 25 years in prison for fatally poisoning boyfriend

MINOT, N.D. — A North Dakota woman will serve 25 years in prison for the poisoning death of her boyfriend, who authorities say believed he was about to come into a large inheritance and had planned to break up with her.

Ina Thea Kenoyer was charged with murder in October 2023 for the death of 51-year-old Steven Riley Jr. Riley was hospitalized and died Sept. 5, 2023, after falling ill and losing consciousness, according to court documents.

An autopsy found he died from ethylene glycol poisoning, according to a Minot police officer's affidavit. Ethylene glycol is used in antifreeze.

Kenoyer pleaded guilty in May. State District Judge Richard Hagar on Wednesday accepted attorneys' joint sentencing recommendation of 50 years in prison — for Kenoyer to serve 25 years, with 25 years suspended — along with 10 years of supervised probation and $3,455 in restitution paid to Riley's family, The Minot Daily News reported.

She faced up to life in prison without parole on the charge.

Riley's friends and family contacted Minot police with concerns that Kenoyer had poisoned him with antifreeze, according to the affidavit. His friends told investigators his health rapidly declined at the airport, where he went to meet a lawyer to complete the inheritance transaction, the officer wrote.

Authorities said Kenoyer claimed Riley had been drinking alcohol all day and suffered heat stroke in the days before his death. Kenoyer knew of the inheritance, which she thought was over $30 million and felt she was due a portion of as Riley's common-law wife, according to the affidavit.

North Dakota does not recognize common-law marriages. Investigators doubted the inheritance existed, according to the newspaper.