A Las Vegas man pleaded guilty Thursday in Mendocino County Superior Court to the voluntary manslaughter of his wife, even though she was shot and killed Dec. 21 by a sheriff’s deputy.

Prosecutors argued that Joseph Charles Mantynen, 32, provoked the deputy to fire by pointing a stolen Remington .22-caliber rifle at law enforcement during an hourlong standoff at the Sunrise Inn in Ukiah, said Mendocino County District Attorney’s Office spokesman Mike Geniella.

Mantynen was originally charged with the murder of his wife, Mary Mantynen, 23, who was on the run from a parole violation in Nevada.

The lethal shot fired by Deputy James Ellmore went through Joseph Mantynen’s bulky clothing and struck his wife, who was the mother of two young sons and a stepdaughter, Geniella said. She died on the bathroom floor of the motel room.

The Mantynens were tracked to the motel by a Sonoma County sheriff’s detective who was investigating a burglary of Joseph Mantynen’s grandmother’s home in Sonoma County where the Remington rifle was taken, Geniella said.

Sonoma County deputies spotted Joseph Mantynen outside the motel around 7 p.m. He ran into the motel room and picked up the rifle, Geniella said, before pointing it at law enforcement. Sonoma County Deputy Scott McKinnon shot at him but missed.

Ukiah police and the Mendocino County Sheriff’s SWAT Unit arrived for backup.

Joseph Mantynen later told investigators that he and his wife had planned “suicide by cop” if they could not escape, Geniella said.

In pleading guilty to voluntary manslaughter and three other felonies, Joseph Mantynen agreed to a 26-year and four-month term in state prison, Geniella said. He was be officially sentenced March 28.

You can reach Staff Writer Nick Rahaim at 707-521-5203.