Man pleads guilty to fatally stabbing wife near sheriff's substation

Marvin Duncan to be sentenced in July

CHULA VISTA, Calif. - A San Diego man who fatally stabbed his estranged wife in a parking lot at a South Bay sheriff's substation earlier this year pleaded guilty Wednesday to first-degree murder.

Marvin Dennis Duncan, 60, is due to be sentenced on July 26. He faces a stipulated 25 years to life in prison.

Shortly after 3:30 p.m. on Feb. 6, Duncan pressed an intercom button at a side door at the precinct house on Imperial Beach Boulevard, said sheriff's homicide Lt. Glenn Giannantonio. When a deputy answered, Duncan, who was holding two toddlers, announced he had just killed his spouse, according to the lieutenant.

The mortally wounded victim -- Duncan's 36-year-old wife, Rocio -- was found lying on the ground on the west side of the substation. She died a short time later.

Duncan was detained for questioning and later arrested. The children, who were unharmed, were taken into protective custody. The motive was under investigation.

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